THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


R,  L,  CROCKETT,   M.  D, 


STRABISMUS,  OR  SQUINT 

£Sw 

LATENT  AND  FIXED 
A  SUPPLEMENT  TO  THE 

ERRORS   OF   REFRACTION 


-,,..  ,,  _ 

BY 


FRANCIS  VALK,  M.D. 

Professor  of  Diseases  of  the  Eye,  New  York  Post-Graduate  School  and  Hospital; 

Consulting  Ophthalmologist,  Thrall  Hospital;   and  formerly  Assistant  Sur- 

geon, Manhattan  Eye  and   Ear  Hospital  ;   Visiting   Ophthalmologist 

Randall's  Island  Hospitals,  and  Ophthalmologist  to  the  New  York 

Dispensary.     Fellow  of  the  New  York  Academy  of  Medi- 

cine and  of  the  State  and  County  Medical  Society. 

Member  of  the  Greater   New  York   Medical 

Society  and  the  Society  of  Medical  Juris- 

prudence, etc. 


G.  P.  PUTNAM'S  SONS 

NEW   YORK  AND    LONDON 

Ube  Iknicfeerbocfeer  press 

1904 


COPYRIGHT,  1904 

BY 
FRANCIS  VALK 


Published,  July,  1904 


Ube  f?nfcherbocfeer 


LuU 
iU$ 

1/2  3 


To  the  memory  of  my  Father, 
HON.    WILLIAM    WHITEMAN    VALK,    M.D., 

SURGEON,    4TH    MARYLAND    VOLS.,     U.   S.   A., 

this  work  is  affectionately  dedicated, 

in  respectful  admiration  of  his  work 

as  a  physician  and  surgeon. 


CONTENTS. 

CHAPTER  PAGE 

PREFACE        .......  v 

I.     ARGUMENT    .......  i 

II.     MOVEMENTS  OF  THE  EYES  ....  5 

III.  CLASSIFICATION  OF  SQUINT.         ...  32 

IV.  ESOPHORIA,  OR  LATENT  CONVERGENT  SQUINT  36 
V.     EXOPHORIA,  OR  LATENT  DIVERGENT  SQUINT  47 

VI.     HYPERPHORIA,  OR  LATENT  VERTICAL  SQUINT  77 
VII.     STRABISMUS    OR    SQUINT,  CONCOMITANT   OR 

FUNCTIONAL      ......  89 

VIII.     ILLUSTRATIVE  CASES    .         .         .         .         .123 

IX.     INDICATIONS  FOR  OPERATIONS      .         .  133 

X.     OPERATIONS  FOR  SQUINT      ....  142 

XI.     AFTER-TREATMENT  OF  SQUINT      .         .         .15? 

INDEX.          .......  165 


ILLUSTRATIONS. 

FIGURE  PAGE 

Frontispiece               .  .  .            i 

Tropometer  of  Stevens        .             .  .  57 

Scale  for  Tropometer           .             .  .  •         59 

Skeels  Perimeter                    .             .  .  .63 

Case  of  Square  Prisms         .             .  .  -65 

Maddox  Simple  Rod           .             .  .  .67 

"         Compound  Rod                .  .  .67 

"         Double  Prism       .              .  .  .86 

Diagram  of  Cyclophoria       .              .  .  .86 

Clinoscope  of  Stevens          .             .  .  .87 

Estimation  of  Angle  "  A  "                 .  .  .112 

Internal  and  External  Check  Ligaments  .  .  121 
Instruments :  .....  144 
Exposure  of  the  Muscle,  ....  147 

Position  of  the  Needle  and  Suture  .  .148 

Twin  Strabismus  Hooks       .             .  .  .148 

Capsules  of  Catgut,  o  or  oo              .  .148 

The  Suture  Tied,                   .              .  .  .149 

Amblyoscope,  Worths          .              .  .  160 


PREFACE 

I  HAVE  been  repeatedly  asked  if  I  had  issued  a  revised 
edition  of  my  work  on  the  "  Errors  of  Refraction"  and 
have  answered  that  question  in  the  negative  for  the  reason 
that  since  that  work  was  first  issued  my  methods  of  exam- 
ination of  the  dioptric  media  have  not  changed.  But  the 
subject  of  the  imbalance  of  the  ocular  muscles — during 
the  past  decade — has  attracted  so  much  attention  from 
many  members  of  the  profession  that  I  have  concluded  to 
give  the  results  of  my  personal  experience  with  cases  of 
muscular  imbalance  so  that  my  conclusions  may  be  pre- 
sented to  those  who  are  interested  in  this  work.  Hence 
this  is  partly  a  supplement  to  the  "  Errors  of  Refraction," 
and  my  personal  experience  in  the  examination  and  the 
correction  of  the  imbalance  of  the  eye  muscles ;  while  for 
a  more  extended  study  of  the  subject  I  would  refer  to  the 
many  text-books  offered  by  other  writers,  notably  Maddox, 
on  the  ocular  muscles  and  Hansell  and  Reber,  on  muscular 
anomalies,  etc. 

The  motility  of  the  eyes,  from  that  of  the  normal  bal- 
ance— if  there  is  such  a  condition — through  all  the  various 
grades  of  heterophoria  to  that  of  complete  and  fixed  stra- 
bismus or  squint  has  been  a  subject  of  intense  interest  to 
me  and  while  I  still  think  we  are  hardly  past  the  "  thres- 
hold of  knowledge  "  in  reference  to  this  subject,  yet  the 
advancement  in  this  work  has  been  very  great,  and  rapid 
during  the  past  decade.  From  my  past  experience  and 
present  work  I  have  formed  some  views  and  theories  that 
may  not  have  received  the  full  approval  of  the  profession 
but  they  have  been  very  useful  to  me  in  a  careful  study  of 


vi  PREFACE. 

my  cases  and  in  the  final  improvement  and  cure.  Per- 
haps there  are  many  who  will  not  endorse  my  views,  as 
set  forth  in  these  pages,  but  they  are  founded  on  the 
simple  and  natural  functions  of  the  motility  of  the  eyes 
and  the  obvious  condition  that  nature  intended  in  their 
physiological  action,  and  my  opinions  have  been  strength- 
ened and  confirmed  by  clinical  work  the  more  I 
have  been  enabled  to  watch  and  to  note  the  results  of 
this  work  for  the  past  ten  years.  I  now  present  these 
experiences  and  results — they  all  relate  to  one  subject, 
the  external  muscles  of  the  eye  and  their  imbalance — 
trusting  they  may  be  found  useful  to  the  reader.  I  think 
I  may  claim  that  my  method  of  examination,  the  indica- 
tions and  the  operative  procedure  have  some  measure  of 
originality,  that  will  stand  a  fair  and  crucial  test  or  criti- 
cism and  that  may  be  useful  in  the  many  cases  in  which 
the  desired  relief  has  not  been  obtained  by  the  use  of 
glasses  or  prisms.  I  regret  that  in  the  preparation  of 
this  monograph  on  squint  it  has  seemed  necessary  to 
repeat  my  thoughts  but  the  conditions  are  all  so  intimately 
related,  that  in  the  discussion  of  any  imbalance  the  same 
abnormalities  and  tests  must  arise  thus  making  the  repeti- 
tion of  certain  conditions  and  examinations  necessary,  I 
trust  they  will  not  weary  the  reader  but  serve  to  impress 
upon  his  mind  the  theory  set  forth,  even  if  it  may  not 
meet  with  his  approval.  "  That  a  theory  accords  with  the 
facts  does  not  necessarily  prove  it  true,  although,  until 
some  discordant  fact  is  observed  it  may  serve  some  useful 
purpose."  I  believe  that  the  action  of  the  ocular  muscles, 
in  their  relation  one  to  the  other,  in  reference  to  the 
fusion  power  of  the  eyes  and  the  physiological  processes 
that  govern  their  movements  is  not  fully  understood,  and 
trust  this  work  will,  in  some  way,  assist  others  and 
stimulate  them  to  further  and  more  useful  research  in  this 
most  interesting  field  of  ophthalmology.  I  have  quoted 


PREFACE.  vii 

the  writings  of  many  others  in  this  work  and  am  thankful 
for  the  benefit  these  writings  have  been  to  me  and  for  the 
liberty  of  quotation.  I  wish  to  take  this  occasion  to 
gratefully  acknowledge  my  early  training,  in  the  action  of 
the  ocular  muscles  and  their  standard  test  with  prisms,  by 
my  friend  and  first  instructor  Prof.  D.  B.  St.  John  Roosa, 
in  whose  work  I  have  always  felt  the  deepest  interest,  for 
the  past  twenty-five  years.  To  my  associates  and  assis- 
tants Dr.  E.  M.  Alger — for  his  revision  and  approval — 
and  Dr.  Gertrude  Allen,  I  owe  many  thanks  for  their  sug- 
gestions and  assistance  in  the  preparation  of  this  work. 


Strabismus. 

CHAPTER  I. 

ARGUMENT. 

IF  there  is  any  reason  why  this  treatise  should  be 
offered  to  the  profession  of  medicine  at  this  present  time, 
it  is  in  the  fact  that  there  seems  to  be  no  settled  theory 
as  to  why  the  eyes  should  deviate  or  tend  to  deviate  from 
the  natural  position  of  the  visual  lines  as  evidently  or- 
dained by  nature.  That  they  do  deviate  or  have  a  ten- 
dency to  that  condition  is  a  self-evident  fact,  clearly  shown 
in  numerous  cases ;  but  why  does  an  eye  that  should  be 
normal  assume  or  tend  to  assume  an  anomalous  position? 
This  question  has  never  been  satisfactorily  nor  success- 
fully answered.  Some  eminent  men  have  advanced  their 
theories  of  squint,  either  latent  or  fixed,  but  they  all  have 
met  with  opposition  and  have  not  proved  reliable  from  the 
fact,  that  while  having  many  arguments  favorable  to 
their  theories,  yet  we  see  many  cases,  in  active  practice, 
that  seem  to  disprove  these  theories  completely.  Further- 
more, why  is  it  that  among  all  these  theories,  advanced  in 
reference  to  the  etiology  of  strabismus  or  squint,  no  two 
of  them  seem  to  come  any  where  near  an  agreement  ? 
One  theory  is  advanced  that  will  have  many  followers ; 
another  theory  seems  to  find  the  same  number  of  admirers, 
and  in  simple  justice  I  must  say  that  my  own  theories  on 
this  subject  have  met  with  many  objections.  Yet  as  I 
read  the  text-books  of  to-day  I  see  many  suggestions  that 
point  to  the  muscular  or  anatomical  theory  of  squint. 


2  STRABISMUS. 

There  must  be  one  underlying  cause,  even  though  we  may 
have  so  many  contributing  causes,  and,  just  at  this  point, 
may  we  not  attribute  the  reason  for  such  a  vast  difference 
of  opinion  to  the  fact  that  one  may  very  readily  consider  a 
secondary,  or  contributing  cause  as  the  primal  one,  notably 
so  in  Donders'  Antithesis,  yet  careful  examination,  by  the 
most  advanced  methods  of  the  present  day,  will  demon- 
strate one  condition  always  present  in  every  case  of  devia- 
tion of  the  visual  lines.  If  so,  it  seems  reasonable  to  me, 
that  such  condition  must  be  the  one  true  and  prime  cause  of 
all  cases  of  Strabismus,  either  fixed  or  latent  and  in  any 
and  all  directions. 

Theoretical  considerations  of  this  subject  will  not  do. 
The  eyeball  is  not  a  camera.  Its  action  as  to  rays  of  light 
differs  from  that  of  a  box  or  lens.  The  ocular  muscles 
are  not  the  "  reins  to  drive  a  horse  "  or  simply  to  mechan- 
ically move  the  eyeballs  in  and  out  and  up  and  down,  but 
these  beautiful  anatomical  structures  of  the  eyes  are  con- 
trolled and  adjusted  according  to  the  laws  of  nature 
and  also  controlled  by  the  human  being  "  behind  it 
all "  that  must  influence  them  in  many  ways.  Then 
behind  all  this  beautiful,  complex,  and  intricate  system  of 
tissues,  (nerves,  muscles  and  vessels),  we  find  the  most 
simple  rules  and  observations  to  point  out  the  movements 
of  the  eyes  and  the  action  of  the  muscular  apparatus. 
Let  me  illustrate  this  in  the  action  of  the  obliques.  Ac- 
cording to  our  text-books  these  muscles  seem  to  play  a 
very  important  part  in  the  economy  of  the  movements  of 
the  eyes  in  the  field  of  rotation  and  yet,  we  may  ask  our- 
selves if  tire  same  movements  might  not  occur  if  the 
oblique  muscles  were  absent?  If  so,  then  why  shall  we 
consider  them  at  all  ?  Well  we  need  not  in  a  practical 
sense,  but  at  the  same  time  we  must  remember  that  the 
adjustment  of  the  eyes  in  the  orbits  and  that  of  the  verti- 
cal plane  of  one  eye  to  that  of  the  other  eye,  is  so  exact 


ARGUMENT.  3 

that  any  anomaly  of  one  or  more  of  the  straight  ocular 
muscles,  either  due  to  an  anatomical  condition  or  to  a 
paresis,  partial  or  complete,  must  disturb  the  harmonious 
action  of  all  the  others,  in  a  greater  or  less  degree.  So, 
in  the  case  of  any  deviation  or  tendency  to  deviate  we 
must  keep  in  mind  this  beautiful  adjustment  of  our  visual 
lines  and  the  vertical  planes  so  that  we  may  always  pro- 
duce that  priceless  function,  binocular  vision. 

Then  in  the  study  of  all  these  functions  of  the  human 
eye,  these  "  windows  of  the  human  soul  "  we  must  consider 
them  as  acting,  not  as  a  human  machine,  but  as  one  of  the 
most  beautiful  and  complex  systems  of  nature,  and  yet, 
one  that  may  be  demonstrated  as  simple  and  easily  under- 
stood if  we  will  only  look  at  the  subject  in  the  light  of 
nature  and  of  her  work.  As  we  study  the  physiological 
properties  of  the  eyes  and  their  muscular  apparatus,  is  it 
necessary  to  consider  them  as  moved  downward  by  the 
combined  action  of  two  or  three  muscles  or  simply  by  that 
of  one,  the  inferior  ?  We  may  suppose  that  all  of  these 
muscles  act  in  the  function  of  looking  downward,  and 
perhaps  they  do,  for  I  doubt  very  much  that  nature  ever 
placed  a  useless  organ  or  muscle  in  the  body,  and  the  action 
of  these  muscles  that  may  be  accessory  to  the  action  of 
one  muscle  may  be  necessary,  but  to  my  mind  are  not. 
Furthermore,  to  continue  the  argument :  A  paralysis  of 
the  superior  oblique  (which,  by  the  way  is  very  rare) 
will  seem  to  interfere  with  the  function  of  looking  down- 
ward, as  well  as  in  all  other  directions,  but  is  not  this  fault 
due  more  to  the  disturbance  of  all  the  actions  of  the  ocu- 
lar muscles  from  the  paralysis  of  such  an  important  mus- 
cle as  that  of  the  superior  oblique  ?  A  paralysis  of  any 
ocular  muscle  must  disturb  the  action  of  all  the  others  in 
a  greater  or  less  degree  but  I  think  that  in  all  cases  under 
a  carefully-conducted  examination  we  can  locate  just  what 
muscle  is  or  may  be  affected. 


4  STRABISMUS. 

The  subject  of  heterophoria  or  of  squint  is  attracting 
the  attention  of  many  students,  and  with  our  increased 
facilities  for  the  examination  of  the  refraction  and  the 
musculature  of  the  eyeball  that  we  have  at  present,  we 
should  know  and  understand  what  is  the  prime  cause,  what 
lies  beneath  all  the  more  superficial  conditions,  and  when 
we  do  locate  this  cause  I  think  we  may  find  a  reason  for 
all  cases  of  strabismus  or  functional  deviation  of  the  vis- 
ual lines.  Not  a  cause  that  will  cover  some  of  the  cases 
but  one  that  will  cover  all  and  every  case.  We  may  then 
paraphrase  Lincoln's  celebrated  saying :  "  Some  of  the 
cases  may  have  one  cause,  one  cause  may  cover  some  of 
the  cases,  but  we  must  find  one  cause  that  will  cover  all  of 
the  cases,"  and  we  shall  then  come  closer  and  closer  to 
nature's  everlasting  truth. 


CHAPTER  II. 

THE    MOVEMENTS    OF    THE    EYE. 

IT  is  an  easily  demonstrated  fact  that  the  eye  must 
remain  perfectly  still  in  any  one  position  when  the  func- 
tion of  vision  takes  place,  and  as  a  corollary  to  that  we 
might  say  that  the  eye  is  practically  blind  when  moving 
from  one  position  to  another,  inasmuch  as  no  images  can 
be  formed  on  the  retina  as  the  eye  moves  from  one  point 
of  regard  to  another.  Dodge  says  "  the  field  of  clearest 
vision  is  practically  a  point,  namely  that  point  at  which 
we  are  looking  ;  "  but  I  should  be  inclined  to  designate  this 
point  as  a  region  whose  extreme  boundaries,  though  not 
perfectly  defined,  would  form  an  angle  with  the  nodal 
point  of  the  eye  of  about  four  degrees,  and  all  objects 
lying  within  this  region  will  be  clearly  and  distinctly  seen. 
At  the  same  time,  this  region  seems  to  have  a  central 
point  which  tends  to  regulate  and  control  the  fusion  of  all 
images  and  the  fixation  of  the  eye.  This  is  the  point  at 
which  the  visual  line  ends,  as  it  is  extended  through  the 
nodal  point  from  the  object  looked  at.  Now  this  region 
of  most  distinct  vision  is  evidently  that  of  the  macula 
lute  a,  or  yellow  spot,  but  is  more  or  less  extended  on  the 
retinal  field,  and  in  space,  at  a  distance  of  one  foot  from 
the  nodal  point  of  the  eye,  will  include  a  region  of  about 
one  inch  in  diameter.  Within  this  region  vision  is  per- 
fectly normal  at  the  reading  distance. 

It  is  very  evident  then  that  the  eye  could  have  no  con- 
tinuous motion  from  one  side  of  the  page  to  the  other,  that 
is,  from  left  to  right,  but  must  pass  by  little  jerks,  as  it  were, 


6  STRABISMUS. 

and  periods  of  rest,  from  one  point  of  regard  to  another, 
so  that  as  we  read  a  line  across  the  page  the  eye  is 
practically  at  rest  much  longer  than  it  is  in  motion.  Simi- 
larly, we  have  the  very  interesting  experiment  of  Stratton, 
as  to  the  movements  of  the  eye  in  following  a  curved  line, 
like  a  circle.  Here  the  movements  of  the  eyes  were  very 
irregular,  but  always  passing  from  one  point  of  regard  to 
another  by  rapid  movements  and  minute  periods  of  rest, 
as  described  above,  he  says,  "this  path  by  which  the  eye 
passes  from  one  to  another  of  these  resting  places  does 
not  seem  to  depend  very  nicely  upon  the  exact  form  of 
the  line  observed,"  it  is  extremely  irregular  in  outline, 
whether  the  object,  as  a  curved  line,  be  artistically  made 
or  very  irregular.  The  same  interesting  movements  take 
place  even  when  the  eye  is  moved  from  point  to  point  in 
space,  but  the  movements  of  rest  are  so  slight  that  the 
retinal  impressions  do  not  reach  the  higher  centres  of  the 
brain,  unless  the  impressions  be  very  sharp  and  vivid. 
To  illustrate  this,  if  we  stand  in  a  darkened  room  and 
look  at  the  electric  spark  of  the  static  machine  at  a  dis- 
tance of  six  feet,  and  then  slowly  move  the  eyes  from  right 
to  left,  we  will  see  a  series  of  minute  bright  spots,  with 
dark  spaces  appearing  between  them  about  two  or  three 
mm.  apart. 

It  must  be  evident  from  this  that  the  eye  during  its 
excursion  from  right  to  left  must  have  made  a  series  of 
minute  stops  sufficiently  long  to  allow  this  intense  image 
to  be  formed  on  the  retina  and  so  conveyed  to  the  brain, 
also  that  no  ijnage  was  formed  while  the  eye  was  in  motion, 
as  shown  by  the  dark  spaces  between  the  brilliant  spots. 
These  phenomena  have  been  long  observed  by  some 
of  our  investigators  in  the  field  of  physiological  sciences, 
and  during  the  past  two  years  have  been  more  fully  inves- 
tigated and  proved  by  means  of  a  reflection  from  the 
cornea  and  a  photographic  plate. 


THE  MOVEMENTS  OF  THE  EYE.  7 

Raymond  C.  Dodge,  Stratton  and  others,  have  made 
many  investigations  in  these  interesting  phenomena,  by 
photographing  a  bright  reflection  on  the  cornea,  as  the 
eyes  are  moved  in  reading,  or  as  the  look  passes  from 
any  point  of  regard  to  another.  If  we  attempt  to  pass  the 
look  slowly  from  one  point  to  another,  so  as  to  see  clearly 
all  the  objects  that  may  be  present  between  these  two 
points,  and  another  person  closely  watches  the  eye  move- 
ments, or  a  photograph  is  taken  of  the  reflection  from  a 
bright  spot  on  the  cornea,  it  will  be  seen  that  the  eye  has 
made  several  rapid  movements  and  stops  from  point  to 
point  across  the  field  of  motion.  This  cannot  be  done 
introspectively  as  we  are  not  conscious  of  these  move- 
ments of  the  eyes  any  more  than  we  are  of  the  similar 
movements  of  fusion  in  the  act  of  binocular  vision. 

My  conception  of  this  physiological  act  is  that  the 
movement  of  the  eyes  from  one  point  of  regard  to  another 
is  purely  a  voluntary  one,  controlled  by  the  higher  brain 
centres,  while  their  action  in  the  fusion  of  the  images 
according  to  physiological  law  is  controlled  by  the  lower 
or  automatic  brain  centres. 

Furthermore,  under  this  voluntary  movement  of  the 
eyes,  as  the  look  passes  from  one  point  of  regard  to 
another,  sufficiently  far  apart,  we  are  practically  blind 
during  the  period  of  transition.  In  other  words,  we  are 
not  conscious  of  any  object  In  the  line  of  movement, 
though  we  may  know  that  the  most  sensitive  part  of  the 
retinal  field  must  have  passed  the  rays  of  light  from  such 
objects.  It  is  true  that  we  may  be  conscious  of  these 
objects,  but  unless  we  were  familiar  with  their  appearance 
we  could  not  tell  what  they  were ;  consequently  when  the 
eyes  pass  from  two  distant  points,  say  ten  feet  from  the 
eyes,  and  separated  fifteen  feet,  we  see  the  two  points 
clearly,  but  not  the  intervening  objects  ;  and  if  we  attempt 
to  move  the  eyes  slowly  between  these  two  points,  so  as 


8  STRABISMUS* 

to  see  all  the  objects  between  them,  the  eyes  will  make  a 
number  of  stops  and  rapid  movements  of  which  we  are 
totally  unconscious. 

Dodge  has  proposed  five  type  of  eye-movements  in  the 
horizontal  meridian,  as  those  of  Fixation,  Pursuit,  Co-or- 
dinate compensation,  Reactive  compensatory,  and  lastly, 
Unique  movements,  which  seem  to  me  are  the  movements 
of  fusion.  The  first  three  are  very  important  in 
connection  with  this  study  and  show  how  extremely  deli- 
cate and  perfect  is  the  adjustment  of  the  visual  line  by  the 
action  of  the  muscles  of  the  eye.  The  first  type,  Fixation, 
are  reactions  to  eccentric  retinal  stimulation  that  seem 
to  be  dependent  on  a  physiological  function  from  birth 
-and  are  not  influenced  by  voluntary  effort.  The  second, 
Pursuit  movements,  are  the  involuntary  movements 
of  the  eye  as  we  look  at  an  object  from  a  moving  train,  in 
which  the  "  line  of  regard  seems  to  lag  behind  the  line  of 
interest  and  to  overtake  it  from  time  to  time  by  short 
eye  movements  of  the  first  type."  The  third  type  is  of 
interest  as  showing  the  constant  fixation  of  the  visual  line 
while  the  head  is  moved  slowly  from  side  to  side. 

Rudolph  Panse,  Archives  of  Otology,  on  Vertigo  :  says, 
"we  judge  of  the  position  of  objects  laterally  by  the  de- 
gree of  ocular  movements,  which  in  turn  is  determined  by 
the  amount  of  innervation  supplied  to  the  muscles.  This 
estimation  takes  place  through  nervous  processes  of 
which  we  are  unconscious.  If  the  ocular  muscles  should 
be  weakened  the  necessarily  increased  innervation,  for  its 
movements  gives  the  impression  of  a  greater  excursion." 

I  have  dwelt  thus  briefly  on  the  various  movements  of 
the  eyeballs  in  the  orbits  to  show  how  delicate  and  yet 
how  exact  all  the  physiological  movements  of  the  eye 
in  the  adjustment  of  the  visual  line  must  then  be  in  the 
function  of  perfect  binocular  vision.  Then  the  question  of 
greatest  importance  is  the  adjustment  of  the  visual  line 


THE  MOVEMENTS  OF  THE  EYE.  g 

and  the  anomalies  that  may  be  present  in  the  muscles 
by  which  these  functions  are  produced,  and  by  what  con- 
ditions they  may  be  disturbed.  By  these  questions  we 
are  brought  to  a  consideration  of  the  ocular  muscles,  their 
action,  their  size,  and  their  insertion  into  the  sclera. 

In  the  ocular  movements,  both  voluntary  and  involun- 
tary, we  are  not  concerned — when  studying  strabismus — 
as  to  just  how  many  muscles  may  participate  in  any  one 
certain  movement.  These  functions  are  referred  to  in 
our  text-books,  but  in  this  study  we  shall  only  consider 
the  action  of  the  interni  in  the  inward  movement, 
or  the  externi  in  the  outward  movement,  and  leave 
out  whatever  participation  the  superior  and  inferior 
may  have  in  the  lateral  movements  of  the  eye.  We  shall 
also  omit  the  action  of  the  oblique  in  the  upward  and 
downward  rotation.  These  oblique  muscles  only  tend  to 
keep  the  vertical  meridians  parallel  with  each  other,  and 
have  no  connection  with  our  consideration  of  the  subject 
of  squint.  In  making  this  statement  I  am  well  aware  that 
the  investigations  of  Stevens  and  Savage  would  lead  us  to 
the  very  complex  study  of  an  insufficiency  of  the  oblique, 
but  the  participation  of  these  muscles  in  the  anomalies  of 
the  straight  .muscles  has  not  yet  been  fully  demonstrated, 
nor  have  I  met  with  any  cases  where  a  weakness  of  the 
obliques  could  possibly  be  shown  unless  there  was  some 
pathological  condition  present. 

I  do  not  propose  to  demonstrate  the  anatomy  nor  the 
physiology  of  these  muscles,  except  so  far  as  we  may  wish 
to  understand  their  action  in  our  daily  work  nor  shall  I 
try  to  form  any  special  theory,  or  follow  the  text-books 
on  this  subject,  but  simply  to  illustrate  what  nature  in 
her  beautiful  work  intended  as  the  functions  of  the  eyes 
and  the  muscular  apparatus.  Perhaps  I  offer  a  theory, 
but  if  so  it  is  one  that  has  been  suggested  to  me  as  I  have 
examined  my  cases  in  daily  practice.  Clinical  work  in 


IO  STRABISMUS. 

the  hospital  gives  us  some  very  valuable  suggestions,  but 
few  have  the  time — in  the  rush  of  a  clinic — to  fully  study 
the  various  phenomena  that  may  be  noted.  But  in  our 
office  work,  where  the  individual  responsibility  comes 
upon  us,  we  must  stop  to  think  of  the  points  that  develop 
as  the  work  proceeds,  and  to  ask  ourselves  why  certain 
phenomena  occur. 

In  trying  to  find  an  answer  to  these  questions  that 
arise,  I  have  endeavored  to  understand  what  was  the 
natural  action  of  these  muscles,  or  in  other  words,  what 
purpose  did  nature — in  the  full  understanding  of  all  her 
requirements — intend  that  the  eye  muscles  should  per- 
form in  the  natural  course  of  life.  Let  me  start  out  with 
the  statement  that  in  this  study  we  will  not  consider  the 
origin  of  the  ocular  muscles,  they  all  come  from  practi- 
cally the  same  region,  except  the  inferior  oblique. 
Leaving  out,  then,  from  our  consideration,  the  complex 
movements  of  the  oblique  muscles,  it  is  with  the  straight 
muscles  of  the  eyes,  their  insertion  into  the  sclera  and  their 
size  and  weight,  where  we  shall  find  the  most  interesting 
points  and  by  which  we  may  understand  what  nature 
intended  should  be  the  normal  action  of  the  ocular  mus- 
cles and  the  reasons  for  the  various  anomalies  that  may 
exist.  In  the  anatomy  of  the  other  parts  of  the  body,  as 
the  muscles  of  the  extremities,  we  find  that  the  needs  of  the 
body  have  been  fully  provided  for,  as  the  parts  that 
require  the  most  power  and  action  have  the  largest  and 
most  powerful  muscles.  Furthermore,  if  we  compare  the 
anterior  with  the  posterior  aspects  of  the  arm  or  leg,  do 
we  not  find  one  much  more  developed  than  the  other  ? 
then  we  may  justly  look  for  the  same  wise  provision  of 
nature  in  the  eyes.  They  are  the  only  parts  of  the 
human  body  that  never  seem  to  be  at  rest,  as  it  is  claimed 
that  the  eyes  move  even  during  profound  sleep. 

Anatomically,  our  first  consideration  will  be  the  insertion 


THE   MOVEMENTS  OF   THE   EYE.  II 

of  these  muscles  into  the  eyeballs  and  Fuchs' results  may 
be  accepted — even  though  we  may  find  great  irregularity 
in  many  cases — as  I  believe  his  results  will  be  found  cor- 
rect and  to  my  view  they  seem  to  point  out  nature's 
intentions.  Quoting  from  Norris  and  Oliver's  System, 
we  have,  first,  the  distance  of  the  insertions  of  the  ocular 
muscles  from  the  cornea  and  Fuchs' results  give  us  these 
figures  : 

Internal  rectus,  =5.5  mm. 

Inferior  rectus,  ==6.5  mm. 

External  rectus,  =6.9  mm. 

Superior  rectus,  =  7.7  mm. 

If  the  assertion  is  true  that  the  nearer  to  the  cornea  we 
find  the  insertion  of  a  muscle,  the  greater  do  we  find  the 
power  of  that  muscle  to  turn  the  eyeball,  then  a  glance  at 
this  table  will  show  the  relative  power  that  nature  intended 
should  be  exercised  by  those  muscles.  But  let  us  con- 
tinue our  investigations  anatomically  a  little  further  and 
see  what  is  the  relative  gross  weight  of  these  muscles  ? 
and  from  the  same  authority,  we  note  Vblkman  quoted  as 
follows : 

Internal    rectus,  =,747  grammes. 
Inferior    rectus,        .671  " 

External  rectus,  =.715  " 

Superior  rectus,  =.514  " 

Again  a  study  of  these  figures  will  give  us  the  same 
results  as  we  had  in  the  insertion  of  the  muscles,  as  we 
find  the  greatest  weight,  as  well  as  the  most  advantage- 
ous insertion,  is  according  to  the  daily  needs  of  these 
muscles  for  action.  Hence,  we  have  here  two  very 
important  factors  that  seem  to  show  the  natural  action  of 
the  straight  muscles  of  the  eyes. 

What  are  the  movements  of  the  eyes — in  the  function 
of  binocular  vision — that  seem  most  necessary  in  our 


1 2  STXABJSMUS. 

daily  life  ?  First,  the  lateral  movements,  associated  with 
convergence,  and  so  we  may  expect  and  find,  that  the 
muscles  that  produce  these  movements  will  have  the 
greatest  size  and  the  best  insertion,  furthermore,  as  con- 
vergence  is  an  addition  to  the  lateral  movements,  we  find 
that  the  internus  is  the  largest  in  size  with  its  insertion 
nearest  to  the  cornea.  Next  to  that  muscle  is  the  exter- 
nus,  that  can  only  turn  the  eye  outwards.  Then  we  have 
the  inferior,  as  we  are  required  to  look  downward  much 
more  often  than  upward,  and  lastly  we  have  the  superior, 
that  we  find  is  the  weakest  of  the  straight  muscles  of  the 
eye.  Now  if  this  is  nature's  anatomical  arrangement  of 
these  muscles,  do  they  not  convey  a  certain  relation  to 
each  other  in  the  necessities  of  life  ?  and  if  so,  may  we 
not  ask  what  is  this  relation? 

Thomas  Dwight,  M.D.,  LL.D.,  in  Norris  and  Oliver's 
work,  says  :  "  Practically,  it  is  to  be  remembered  that  it  is 
very  unlikely  that  one  or  even  two  of  these  muscles  ever 
act  alone.  The  accuracy  of  any  movement  is  due,  not 
alone  to  the  pull  of  the  muscle  to  which  it  is  usually 
ascribed,  but  also  the  graduated  resistance  of  the  antago- 
nists. Probably  the  simplest  movement  of  the  eye  is 
made  by  the  more  or  less  active  concurrence  of  all  the 
muscles."  This  seems  very  well  in  theory,  but  can  it  be 
proved  by  any  actual  demonstration  on  the  living  sub- 
ject ?  And  if  it  is  only  theory,  will  not  the  supposition 
that  each  muscle  has  its  particular  function  in  the  human 
economy  of  the  eye  do  just  as  well,  and  at  the  same  time 
assist  us  very  much  in  the  study  of  our  cases  and  the 
means  of  relief  if  needed  ?  I  am  inclined  to  think  so, 
and  will  endeavor  to  give  my  conception  of  their  action. 

The  movements  of  the  eyeballs  about  their  centres  of 
rotation  is  a  subject  that  has  been  so  freely  discussed  that 
a  further  consideration  may  not  be  necessary,  but,  at  this 
time  the  action  of  the  ocular  muscles  and  their  deficiency 


THE  MOVEMENTS   OF   THE  EYE.  ^ 

in  power  is  attracting  a  great  deal  of  attention  from  the 
profession,  and  so  the  individual  opinion  of  one  who  has 
studied  the  subject  somewhat  may  be  of  service.  I  am 
inclined  to  simplify  the  action  of  these  muscles  so  as  to 
give  each  one  its  action  in  a  very  simple  manner  and  to 
discuss  how  they  will  act,  either  singly  or  combined,  by 
their  associated  movements,  their  voluntary  and  involun- 
tary action  and  to  entirely  separate  the  action  of  the 
obliques  from  that  of  the  straight  muscles. 

If  one  will  read  of  the  action  of  these  muscles  in  Fuchs' 
Text  Book  of  Ophthalmology,  page  576,  he  will  find  one 
of  the  best  descriptions,  and  I  would  refer  the  reader  to 
that  work,  but  I  think  that  each  muscle  receives 
its  innervation  from  the  nerve  centres,  as  it  is 
necessary  to  turn  the  eyes,  and  a  careful  study  in  this 
direction  will  show  that  there  is  no  necessity,  nor  proof 
that  the  eye  will  require  the  action  of  three  muscles  to 
turn  inward,  etc. 

All  these  muscles  act  by  their  natural  tonicity  to  keep 
the  eyes  steady  in  a  fixed  position  when  at  rest  or  in  the 
first  position.  As  simple  antagonists  when  the  eyes  are 
moved  from  that  position,  and  by  their  innervation  the 
eyes  can  be  turned  to  any  point  by  the  straight  muscles 
alone.  Can  we  not  turn  the  eyes  inward,  as  far  as  neces- 
sary, by  the  action  of  theinterni ;  outward,  by  the  externi  ; 
upward,  by  the  superior  and  downward  by  the  action  of 
the  inferior  ?  while  the  eyes  can  be  turned  to  any  point 
between  these  positions  by  the  combined  action  of  these 
muscles,  as  upward  and  inward  by  the  interni  and  the 
superior  recti  and  so  on  in  all  other  directions  without  the 
muscular  action  of  the  obliques  ?  Perhaps  our  text-books 
do  not  say  so,  but  the  above  proposition  is  reasonably  true 
and  assists  us  very  much  in  the  study  of  the  correction  of 
an  imbalance  of  these  muscles.  Accepting  this  proposi- 
tion, then  we  can  leave  the  movements  of  the  eyes  to  the 


!4  STXABlStfUS. 

straight  muscles  alone  and  find  that  the  oblique  muscles 
will  receive  their  innervation  to  turn  the  eyeballs  on  the 
sagittal  axis  so  as  to  keep  the  vertical  meridians  of  each 
eye  parallel  to  each  other.  This  function  of  the  obliques 
is  entirely  involuntary  ;  we  cannot  cause  them  to  act  alone 
by  any  power  of  the  will,  but  they  are  controlled  and  stim- 
ulated by  the  centre  for  fusion,  or  the  blending  of  the 
images  on  the  retina,  so  that  the  image  of  all  lines  in  the 
vertical  meridians  shall  fall  upon  corresponding  parts.  In 
other  words,  the  action  of  the  obliques  simply  tends  to 
keep  the  vertical  meridians  of  the  eyes  parallel  to  each 
other  and  does  not  assist  in  the  movements  of  the  eyes  in 
the  field  of  fixation. 

Now  the  eye  is  one  of  the  most  perfect  instruments  in 
the  human  economy,  in  which  the  beautiful  adjustment  of 
focal  power  will  bring  all  rays  from  an  object  so  as  to  form 
an  image  on  the  retina,  \vith  each  image  falling  upon  cor- 
responding parts  by  the  action  of  the  straight  muscles  of 
the  eye,  controlled  by  the  fusion  force.  These  rays  from 
the  object  pass  through  the  various  media  of  the  eye  and 
are  refracted  so  as  to  form  the  image,  and  in  these  rays 
we  find  one  central  ray,  passing  from  the  center  of  the 
object  to  the  center  of  the  image  on  the  retina  without  any 
deviation  whatever,  and  this  ray  forms  practically  the  visual 
line,  all  other  rays  being  refracted,  except  those  forming 
the  secondary  axes. 

If  nature  has  provided  for  this  beautiful  adjustment  of 
the  vision,  then  I  think  we  can  trust  her  in  the  movements 
of  the  eyes  for  the  purpose  of  binocular  vision  and  bear 
this  in  mind  witen  we  attempt  to  study  the  different  actions 
of  the  eye  and  the  muscles  by  which  the  eyes  are  moved 
in  various  directions.  May  we  not  ask  the  questions,  first, 
what  is  nature's  object  in  the  movements  of  the  eyes  ? 
and  secondly,  how  has  she  provided  for  those  movements 
that  are  necessary  for  our  well-being  ?  Shall  we  study 


THE  MOVEMENTS  OF  THE  EYE.  lc 

them  simply  from  her  standpoint,  or  shall  we  put  the  eyes 
in  a  position  that  nature  never  intended  they  should  be  in, 
and  then  try  to  find  out  what  is  the  action  of  the  straight 
muscles  or  that  of  the  obliques?  I  am  led  to  this  inquiry 
as  I  find  many  observers  seem  to  draw  their  conclusions 
from  certain  tests  after  they  have  put  the  eyes  in  a  condi- 
tion that  is  practically  abnormal. 

To  be  more  explicit  we  are  told  that  we  may  find  a  par- 
esis of  the  obliques  by  turning  the  eyes  to  their  extreme 
limits,  in  certain  directions,  and  there  find  a  tipping  of 
the  image,  while  on  the  other  hand,  when  the  eyes  are  in 
their  normal  position  we  will  not  have  this  tipping  in  any 
direction.  It  is  the  same  in  the  various  tests  that  have 
been  suggested  to  us  for  a  deficiency  in  the  power  of  the 
straight  muscles,  as  by  the  vertical  diplopia  test,  we 
entirely  destroy  the  fusion  power  and  then  ask,  if  the 
muscular  power  is  below  normal  standards.  The  same 
objection  applies  to  the  tests  with  the  Phorometer  and 
the  Rod. 

If  these  objections  are  practical,  shall  we  not  keep  the 
eyes  as  nature  intended  them  to  be  and  then  endeavor  to 
find  out  if  there  is  any  fault  in  the  muscular  action?  It 
seems  so  to  me,  and  from  that  standpoint  I  have  tried  to 
base  all  my  conclusions  as  regards  the  action  of  the  ocular 
muscles.  We  have  then  two  natural  functions  in  the 
movements  of  the  eyes ;  one  that  is  principally  under  the 
control  of  the  will,  the  power  to  direct  the  eyes  to  certain 
points,  a  fixing  power,  and  one  that  is  not  under  the  con- 
trol of  the  will,  automatic,  the  fusion  power.  The  first 
function  tends  to  keep  the  visual  lines  fixed  on  the  object 
and  the  second  tends  to  keep  the  images  on  corresponding 
parts  of  the  retina.  These  functions  are  controlled  by 
different  parts  of  the  brain  and  to  them  we  may  add, 
the  function  of  convergence  controlled  by  a  special  cen- 
ter. 


1 6  STRABISMUS. 

Hence,  in  the  muscular  system  of  the  eyes,  it  seems  to 
me  we  have  three  forces  acting,  that  are  partly  voluntary 
and  partly  involuntary.  In  the  first  action  we  have  the 
power  to  move  the  eyes  in  all  directions  as  the  will  may 
direct,  the  field  of  fixation,  a  power  that  is  controlled 
entirely  by  the  action  of  the  will-power  of  the  brain. 
This  power  enables  us  to  look  in  all  directions  by  the 
action  of  the  four  recti,  acting  either  singly  or  in  combi- 
nation with  one  or  more  of  the  other  muscles,  and  the 
action  of  these  muscles  is  controlled  by  the  centers  of 
motility  of  the  eyes.  Secondly,  we  seem  to  have  the 
power  to  move  the  eyes — one  independent  of  the  other— 
by  which  we  are  enabled  to  keep  the  images  fixed  on  the 
macula  of  each  eye.  This  power  seems  to  be  an  invol- 
untary one,  as  we  cannot  control  it  by  any  power  or  action 
of  the  will.  This  is  the  fusion  power  of  the  eyes  or  as 
Savage  so  well  puts  it,  the  guiding  sensation,  which 
seems  to  be  controlled  by  a  different  center  of  the  brain 
than  that  which  controls  the  motility  of  the  eyes.  Lastly, 
we  have  the  power  of  convergence,  also  controlled  by  a 
separate  centre  of  the  brain — well  shown  in  paralysis  of 
convergence — which  acting  on  the  interni  from  the  first 
position  to  that  of  extreme  convergence  gives  binocular 
vision  of  all  objects  situated  within  infinity. 

In  the  study  of  the  action  of  the  ocular  muscles,  the 
fusion  power  of  the  eyes  is  of  the  first  importance.  I 
notice  that  it  is  practically  ignored  by  most  writers  on  the 
motility  of  the  eye,  yet  in  all  our  clinical  work  it  is  a  most 
important  factor,  as  it  is  so  absolutely  necessary  for  the  func- 
tion of  binocular  vision,  as  we  must  have  perfect  fusion 
of  the  images,  on  their  respective  retinas,  to  have  perfect 
binocular  vision  both  at  the  near  and  distant  points.  We 
may  separate  these  images  mechanically — as  I  shall  show 
by  the  action  of  prisms — yet  if  we  do  separate  them,  they 
will  again  fuse  by  an  involuntary  act  controlled  by  some 


THE   MOVEMENTS  OF   THE  EVE.  \j 

center  of  the  brain  and  not  simply  by  the  power  of  the 
will,  until  they  are  so  displaced  that  the  natural  power  of 
the  muscle  is  not  great  enough  to  cause  the  images  to 
fuse,  in  other  words,  the  muscular  system  may  not  be 
strong  enough,  under  the  stimulation  of  the  guiding 
sensation,  to  move  the  eyes  so  that  both  images  will  fall 
upon  the  macula  or  on  corresponding  parts  of  each  ret- 
ina. 

As  nature  "abhors  a  vacuum,"  so  does  she  naturally 
object  to  the  double  images  or  diplopia,  and  when  we  do 
produce  diplopia  by  displacing  the  rays  of  light  from  an 
object,  by  passing  them  through  a  prism,  the  brain 
becomes  aware  of  the  diplopia  and  seeks  to  obviate  it  by 
turning  the  eye  on  its  center  of  rotation  until  we  again 
have  single  vision.  This  can  only  be  controlled  by  the 
innervation  of  the  ocular  muscles  and  this  innervation  can 
only  act  on  the  muscles  according  to  the  relative  power 
to  turn  the  eye  in  a  certain  direction.  If  I  deviate  the 
rays  from  a  candle  outward,  then  the  image  is  formed  on 
the  outer  part  of  the  retina  and  diplopia  results,  but  at 
once,  as  the  fusion  power  is  disturbed  we  find  the  eye 
turning  inward,  until  single  vision  is  again  produced. 
Provided,  the  power  of  the  internus  is  great  enough  to 
turn  the  eye  inward  until  the  deviation  of  the  rays  is  over- 
come and  the  visual  line  will  correspond  with  the  central 
rays  as  they  pass  through  the  prism.  But,  if  the  rays  are 
deviated  so  far  outward  that  the  internus  cannot  turn  the 
eye  sufficiently  inward  then  no  power  of  the  will  can  fuse 
the  images,  and  diplopia  remains. 

This  fusion  power  of  the  eye  is  then  an  involuntary  ac- 
tion, not  only  on  the  straight  muscles  to  keep  the  image 
fixed  on  the  macula,  but  also  on  the  oblique  muscles,  by 
which  we  are  enabled  to  keep  the  vertical  meridian  of 
each  eye  parallel  so  that  the  other  parts  of  the  image,  will 
fall  upon  corresponding  parts  of  each  retina,  as  long  as 


1 8  STRABISMUS. 

the  visual  line  remains  within  the  limits  of  the  field  of  fixa- 
tion. 

Before  we  proceed  further,  with  the  tests  of  these  ocu- 
lar muscles  in  reference  to  their  power  to  move  the  eyes, 
it  will  be  understood  that  all  degrees,  as  represented  by 
prisms,  refer  to  the  angle  of  the  prism  and  not  to  its  devi- 
ating power,  unless  so  expressed.  As  a  simple  rule,  we 
may  understand  that  the  refracting  angle,  or  power  to 
deviate  the  rays  from  an  object  is  one-half  that  of  the 
angle  of  the  prism. 

Proceeding  to  a  further  study  of  the  action  of  these 
muscles,  we  may  note  :  first,  for  the  purpose  of  illustra- 
tion, the  field  of  vision,  which,  as  measured  by  the  peri- 
meter, with  a  small,  square  white  object,  is  outward,  90° ; 
upward,  50° ;  inward,  60° ;  and  downward,  70° ;  these 
measurements  may  vary  somewhat  in  different  individuals. 
This  being  the  extent  of  the  physiological  limits,  in  which 
the  eye  can  distinguish  moving  objects,  when  in  the  first 
position. 

In  the  same  manner  we  find  the  field  of  fixation,  which 
is  represented  by  the  extreme  excursions  that  the  eye  can 
make  in  all  directions  while  the  distinct  image  of  the 
object  will  be  fixed  on  the  macula.  We  know  that  the 
macula  region  of  distinct  vision — and  by  distinct  vision  I 
mean  the  ability  to  see  two  very  small  dots  on  a  white 
card  and  close  together,  or  the  ability  to  read  No.  i 
Jaeger, — is  very  small ;  and  its  region  in  space  about  one 
inch  in  diameter  on  the  page  of  a  book,  held  at  the  usual 
reading  distance.  Then  to  find  the  field  of  fixation,  we 
test  the  eyes"  in  reference  to  the  ability  to  see  these  two 
small  dots,  or  to  read  the  finest  type,  clearly,  in  all  direc- 
tions. We  find  that  this  field  is  represented  by  the  abil- 
ity of  the  eye  to  turn  outward.  I  make  this  statement  as 
it  seems  to  me  that  the  field  of  fixation  inward  is  limited 
for  each  eye,  in  this  test,  by  the  contour  of  the  nose ; 


THE  MOVEMENTS  OF  THE  EYE.  ig 

we  see  clearly  in  the  inner  part  of  the  field  until  the 
object  passes  behind  the  prominence  of  the  nose. 

The  field  of  fixation  may  then  be  expressed  by  the 
power  of  the  straight  muscles  of  the  eye  to  turn  the  visual 
line  in  all  directions,  with  clear  and  distinct  vision  of  the 
smallest  objects. 

DeSchweinitz  gives  the  limitations  of  this  field  or  the 
excursions  of  the  eyeballs,  at  about  90°,  vertically  and 
laterally  :  with  downward  rotation,  60° ;  upward,  30° ;  in- 
ward, 45° ;  and  outward,  40°;  while  an  average  of  Duane's 
measurements  gives  the  rotation,  as  downward,  60° ;  up- 
ward, 43° ;  inward,  47° ;  and  outward,  46° ;  these  results 
are  about  the  same  as  found  in  my  own  measurements 
of  the  same  field,  using  the  finest  type  and  at  the  farthest 
distance  from  the  centre  of  the  perimeter,  that  it  could  be 
read  distinctly. 

Stevens'  measurements  with  the  tropometer,  seem  to  be 
the  most  practical  and  exact,  as  this  is  essentially  an 
objective  examination  depending  on  the  excursions  of  the 
eyeballs.  Measured  by  this  instrument  the  field  of  fixa- 
tion is  very  nearly  the  same,  as  we  find  the  excursions  of 
the  eye,  downward,  50°;  upward,  33°;  inward,  55°;  and 
outward,  50° ;  all  these  measurements  being  practically  the 
same.  There  is  very  little  difference  between  the  objec- 
tive and  the  subjective  fields  of  fixation.  This  power  to 
turn  the  eyes  in  any  direction — limited  by  the  power  of 
the  straight  muscles  of  the  eyes — is  purely  voluntary,  and 
under  the  complete  control  of  the  will  as  far  as  binocular 
vision  is  concerned,  as  in  these  tests,  the  co-ordinating 
power  of  the  eyes  is  the  same  whether  we  cover  one  eye 
or  not,  and  the  monocular  field  is  usually  the  same  in 
each  eye,  unless  we  have  some  anomaly  in  the  action  of 
these  muscles  present,  as  an  insufficiency  of  power  or  a 
paresis.  These  movements  of  the  eyes  have  been  lately 
termed  version,  in  contradistinction  to  that  of  duction, 


20  STRABISMUS. 

and  may  be  designated  as  inward  or  outward  version,  and 
so  on.  I  will  now  call  your  attention  to  what  is  one  of 
the  most  important  functions,  a  third  field  of  vision  in  the 
examination  of  the  eyes,  which  we  will  term  the  field  of 
fusion.  This  field  is  represented  by  the  excursions  of 
the  eye  to  fuse  displaced  images  on  the  retina  in  any  part 
of  the  field  of  fixation.  This  is  a  physiological  function 
that  seems  to  be  almost  involuntary,  and  that  must  be 
controlled  by  a  different  centre  of  the  brain  from  that  of 
the  excursions  of  the  eye  in  the  field  of  fixation,  or  at 
least,  the  muscular  sense  seems  to  be  acted  upon  by  a 
special  centre  different  from  that  which  innervates  the 
movements  of  the  eyeballs  on  the  centre  of  rotation  in 
version.  The  designation  of  duct  ion  to  this  function  is 
very  appropriate,  and  it  can  be  referred  to  as  adduction, 
abduction,  sursumduction  and  deorsumduction. 

In  reading  Morgan  on  Comparative  Psychology,  in  the 
chapter  on  Automatism  and  Control,  I  am  inclined  to 
think  that  this  fusion  power  of  the  eyes  is  controlled  by 
the  lower  centres  of  the  brain  and  is  automatic  in  its  action, 
and  not  by  the  higher  centres  under  the  control  of  the 
will.  .  .  Be  that  as  it  may,  the  centre  for  fusion  has 
not  yet  been  demonstrated,  but  it  seems  to  me  there  must 
be  some  control  over  the  movements  of  the  eye  to  pro- 
duce perfect  binocular  fusion  of  the  images.  All  of  which 
remains  to  be  proved.  DeSchweinitz,  page  507,  says, 
"fusion  is  believed  to  be  the  origin  of  the  impulse  which 
directs  the  movements  of  the  eyeballs,  especially  in  asso- 
ciation in  the  same  direction."  If  this  be  true — and  I 
firmly  believe  ft — then  we  must  change  many  theories  of 
the  movements  of  the  eyes  and  our  tests  for  insufficiency 
of  the  ocular  muscles,  also,  in  my  opinion,  some  of  the 
theories  of  the  causation  of  strabismus.  I  referred  to  this 
fusion  power  in  reference  to  squint,  in  a  paper  read  before 
the  New  York  County  Medical  Society  on  "  Crossed  Eyes  ; 


THE  MOVEMENTS  OF   THE  EYE.  21 

How  shall  we  treat  them  ?"  November  24th,  1894.  Fuchs, 
in  his  text-book,  speaks  of  this  function  as  the  "  tendency 
to  fusion  "  due  to  "  attempting  to  bring  the  eyes  by  suitable 
muscular  effort  into  a  proper  position,  so  that  the  double 
images  coalesce  "  and  illustrates  it  by  the  power  to  fuse 
the  images  when  they  are  separated  by  the  deviating 
action  of  a  prism.  Hence  as  I  understand  it,  the  field  of 
fusion  has  no  reference  to  the  movements  of  the  eyes 
within  the  field  of  fixation,  in  fact,  seems  to  be  completely 
independent  of  the  normal  ocular  movements  of  the  eye- 
balls and  is  practically  dependent  on  the  relative  power  of 
the  straight  muscles.  Then  the  power  to  turn  the  eyeballs 
on  the  centre  of  rotation  has  nothing  to  do  with  this  fusion 
power,  as  each  function  seems  to  me  to  be  separate  and 
distinct. 

To  repeat,  what  are  these  two  functions  of  the  eye, 
and  are  they  not  controlled  by  different  centres  of  the 
brain  ?  First,  we  have  the  power  to  turn  the  eye,  on  the 
centre  of  rotation,  in  any  direction  by  the  innervation  of 
the  straight  muscles  of  the  eye,  which  in  all  persons  is  a 
fixed  power,  as  shown  by  the  field  of  fixation,  as  all  the 
examinations  are  about  the  same,  as  inward  and  outward, 
etc.,  the  limit  generally  between  40°  and  60°.  On  the  other 
hand,  the  excursions  of  the  eyes  to  produce  fusion  of  the 
images  is  very  much  smaller,  the  muscles  must  receive 
their  impulse  from  a  different  centre  of  the  brain  and  the 
limit  of  turning  the  eyes,  so  as  to  fuse  the  images- 
fusion  power — is  evidently  controlled  by  the  relative  power 
of  the  straight  muscles,  which  is  the  same  in  all  positions 
of  the  eyes  in  the  field  of  fixation. 

If  we  turn  the  eyes  to  the  right  20° ;  or  to  the  left  20° ; 
or  upward  or  downward,  we  still  find  this  fusion  power  the 
same  in  all  positions ;  adduction  still  has  the  same  rel- 
ative power  in  reference  to  abduction  in  one  part  of  the 
field  as  the  others,  as  the  images  will  fuse  with  the  same 

o 


22  STRABISMUS. 

prisms  placed  over  the  eye  as  they  will  in  the  primary 
position. 

What  is  this  relative  power  of  the  straight  muscles  of 
the  eyes  ?  Is  it  not  represented  by  the  normal,  physiolog- 
ical action,  anatomical  construction  and  insertion  of  these 
muscles  as  shown  in  the  first  part  of  this  paper  ?  Are  not 
the  natural  needs  of  the  eyes  exactly  represented  by  these 
muscles  as  they  act  in  the  field  of  fusion  ?  I  believe  so,  as 
we  are  required  to  seldom  turn  the  eyes  upward  ;  more 
often  downward  ;  and  constantly  in  a  lateral  direction, 
with  which  we  must  associate  convergence  ;  and  the  limit 
of  the  field  of  fixation  upward,  demonstrates  that  the  weak- 
est muscle  of  the  four  recti  is  strong  enough  to  turn  the 
eye  on  the  centre  of  rotation  to  the  extreme  limit  of  fixa- 
tion, while  the  fusion  power  to  turn  the  eye  upward  is  only 
3°  more  or  less. 

Hence,  the  relative  power  of  these  muscles  has  no  rela- 
tion to  the  power  to  turn  the  eye  in  the  field  of  fixation, 
and  consequently  has  no  reference  to  the  power  of  version, 
as  usually  suggested,  but  simply  to  the  power  of  fusion. 
In  other  words,  I  can  turn  my  eyes  to  the  limit  of  fixa- 
tion, or  say  30°  to  the  right  and  still  fuse  the  images  sep- 
arated by  a  prism,  according  to  the  relative  power  of  the 
straight  muscles,  the  same  as  I  can  when  the  eyes  are  in 
the  primary  position. 

From  the  preceding  remarks,  we  must  have  certain  parts 
of  the  brain  that  seem  to  control  the  movements  of  the 
eyeballs ;  one  that  controls  and  stimulates  the  movements 
of  the  eye  in  its  excursions,  that  is,  that  controls  the 
action  of  the  four  recti.  which  move  the  visual  line  within 
the  field  of  fixation,  the  centre  that  controls  conver- 
gence and  the  centre  that  controls  the  action  of  the 
oblique  muscles  to  keep  the  vertical  meridians  of  the 
eyes  parallel,  simply  turning  the  eyeballs  on  the  sagittal 
axes.  These  centres  control  the  movements  of  the  eyes 


THE  MOVEMENTS  OF  THE  EYE.  23 

to  any  point  in  the  field  of  fixation  and  independently  of 
these  centres  we  have  the  function  of  the  brain  that  is 
stimulated  by  the  guiding  sensation  of  the  eyes  to  pre- 
serve binocular  vision  and  to  prevent  diplopia — within  the 
field  of  fixation — and  that  innervates  the  eye  muscles 
according  to  the  extent  of  the  field  of  fusion. 

What  is  the  extent  of  this  field  of  fusion,  and  how  shall 
we  estimate  it,  as  it  varies  in  different  individuals  ?  This 
will  depend  upon  the  power  of  the  muscles — one  indepen- 
dent of  the  other,  according  to  the  stimulation  of  the 
guiding  sensation — that  can  be  represented  by  a  prism, 
which  will  deviate  the  rays  of  light  from  an  object  so  as 
to  fall  on  some  part  of  the  retina,  distant  from  the  macula, 
and  yet  can  be  fused  or  blended  by  muscular  action. 
This  momentary  diplopia  will  stimulate  the  centre  for 
fusion  and  so  innervate  the  ocular  muscles  to  produce 
single  vision.  The  strongest  prism  with  which  we  can 
produce  fusion  represents  the  power  of  the  eye  to  move 
within  this  field.  I  think  it  best  to  make  all  these  tests 
from  a  distant  point,  as  twenty  feet,  so  that  the  eyes  may 
be  free  from  the  stimulation  of  convergence  with  accom- 
modation and  the  increased  illumination  of  the  near  point. 
Hence  I  place  the  candle  or  other  illuminated  object  at  a 
distance  of  twenty  feet  from  the  patient  and  a  little  lower 
than  the  plane  of  the  visual  line  when  fixed,  so  that  the 
eyes  may  be  in  the  primary  position.  Then  place  a 
good  frame  on  the  face  and  in  this  place  a  prism  with  the 
apex  over  the  muscle  to  be  tested.  In  this  manner  we 
note  the  extent  of  the  field  of  fusion  in  all  directions. 

In  proceeding  with  this  test  we  should  give  the  guiding 
sensation  time  to  act  on  the  innervation  of  the  ocular 
muscles,  commencing  with  the  weaker  prisms  and  increas- 
ing their  strength  as  long  as  the  images  will  fuse  or  blend 
into  a  single  image  of  the  object.  These  tests  will  vary 
from  day  to  day  and  no  conclusions  should  be  reached 


24  STRABISMUS. 

until  they  are  constant  after  several  examinations,  with  a 
short  rest  between  the  examinations  of  the  several  mus- 
cles. It  is  also  advisable  to  test  the  abducting  power  of 
the  externi  first,  as  this  power  is  as  a  rule  more  constant, 
and  its  power  is  also  indicative  of  the  relative  power  of 
the  lateral  moving  muscles. 

In  this  manner  we  proceed  to  test  the  power  for  diverg- 
ence ;  then  convergence  ;  then  sursumvergence  and  lastly 
deorsumvergence,  but  in  all  tests  we  must  vary  the  pro- 
cedure so  as  to  eliminate  any  tendency  to  spasmodic 
action  of  the  muscles. 

Under  the  stimulation  of  the  guiding  sensation  we  find 
that  the  power  of  these  muscles  have  a  certain  relation  to 
each  other,  according  to  their  anatomical  construction 
and  their  insertion  into  the  sclera,  and  I  test  them  as  fol- 
lows :  For  the  externus  or  abduction,  we  place  in  the  trial 
frame  a  weak  prism,  with  the  base  inward  or  toward  the 
nose.  This  causes  the  rays  of  light  from  the  object  to 
deviate  inward  and  fall  upon  the  inner  part  of  the  retina, 
producing  diplopia,  at  once  the  guiding  sensation  through 
the  fusion  centre  will  stimulate  the  action  of  the  externus 
and  the  eye  is  turned  outward  until  the  images  fuse.  As 
they  blend  together  we  then  proceed  to  place  stronger 
prisms  in  the  frame,  until  the  action  of  the  externus  can 
no  longer  fuse  the  images  and  the  strongest  prism  with 
which  single  vision  is  produced  will  represent  the  power 
of  the  externus  to  turn  the  eye  outward  or  the  extent  of 
the  field  of  fusion  in  that  direction. 

We  then  proceed  to  test  the  power  of  adduction  in  the 
same  manner  ahd  after  these  results  have  been  noted,  we 
test  the  power  of  the  eyes  to  turn  upward  and  lastly 
downward,  with  very  weak  prisms.  After  these  tests  of 
all  the  straight  muscles  have  been  carefully  made  and  the 
results  noted,  we  will  not  only  find  a  very  decided  differ- 
ence in  the  power,  but  also  that  this  power  of  each  mus- 


THE  MOVEMENTS  OF  THE  EYE.  95 

cle  bears  a  certain  relation  to  its  opposite  or  antagonist 
muscle. 

The  power  of  the  externi,  in  the  normal  eye,  is  usually 
about  6° ;  the  power  of  the  interni,  about  20° ;  that  of  the 
superior,  about  2°,  and  that  of  the  inferior  somewhat 
stronger  than  the  superior,  and  the  relative  values  would 
be  represented  as  about  three  to  one  for  the  lateral  mov- 
ing muscles  and  about  one  and  one-half  to  one  for  the 
vertical  muscles.  Now  this  relative  power  is  very  im- 
portant, as,  if  they  keep  their  relation,  one  to  the  other,  I 
do  not  think  it  makes  much  difference  what  may  be  the 
actual  power  of  the  muscles  to  turn  the  eyes  under  the 
influence  of  the  guiding  sensation.  For  instance  if  the 
externi  should  show  a  power  of  10°,  then  I  would  want  to 
find  the  power  of  the  interni  nearly  30°,  or  if  the  externi 
should  only  show  3°  then  the  power  of  the  interni  should 
not  be  above  icr  to  12°  with  the  vertical  acting  muscles 
in  the  proportion  as  noted  above. 

I  have  accepted  this  relative  power,  after  careful 
examination  of  many  cases  and  feel  assured  that  when  we 
find  the  relative  balance,  after  repeated  trials,  as  previously 
suggested  we  cannot  have  an  insufficiency  of  the  muscular 
balance. 

Other  observers  seem  to  have  arrived  at  somewhat  dif- 
ferent conclusions  in  reference  to  the  standard  power  of 
these  ocular  muscles,  but  they  give  about  the  same  rela- 
tive power,  and  each  one  must  form  his  own  conclusions 
from  the  examinations  made  personally,  while  cases  that 
will  show  a  much  higher  degree  of  muscular  power  or  a 
larger  field  of  fusion,  are  very  rare.  But  in  all  cases  I 
believe  that  the  most  essential  point  is,  that  the  relative 
power  of  these  muscles  should  be  as  suggested, 
and  if  so,  the  eyes  will  be  free  from  any  muscular  defi- 
ciency whatever. 

If  this  relative  power  is  dependent  on  the  guiding  sen- 


26  STRABISMUS. 

sation  we  may  see  the  importance  of  preserving  this  func- 
tion in  all  our  tests,  as  Savage  well  says,  page  125,  "All 
of  the  center  of  the  oculo-motor  nucleus  have  one  com- 
mon master,  which  is  the  guiding  sensation,  residing  in 
the  retina,  its  home  being  the  macula  lutea,  and  its  imme- 
diate neighborhood."  Hence,  I  have  no  confidence  in 
any  tests  of  the  power  or  the  weakness  of  these  muscles 
that  deprive  the  eye  of  this  most  important  function, 
except  so  far  as  they  may  be  confirmatory  of  the  prism 
test  as  suggested  and  as  fully  demonstrated  in  my  paper 
on  the  "  Power  of  the  Interni,"  read  before  the  Ophthal- 
mic Section  of  the  New  York  Academy  of  Medicine, 
November  19,  1893. 

I  shall  not  present  the  arguments,  for  or  against  this 
method  of  testing  the  ocular  muscles,  that  have  been  pre- 
sented by  many  writers,  —  Noyes  seems  to  depend  on  the 
same  tests  that  I  have  advanced  ;  also,  Bannister's  Mono- 
graph shows  the  same  field  of  fusion.  Others  do  not 
seem  to  claim  any  power  or  virtue  in  the  guiding  sensa- 
tion, but  simply  base  their  conclusions  on  the  tendency 
that  the  eyes  have  to  turn  in  certain  directions  when 
deprived  of  this  function.  Furthermore,  I  would  not  dis- 
cuss the  theory  that  in  testing  one  muscle  in  this  manner 
we  are  simply  estimating  the  power  of  its  antagonist  of 
the  other  eye,  as  we  will  meet  with  many  cases  that  are  by 
no  means  simple  in  their  final  results.  I  have  endeavored 
to  study  this  muscular  action  in  the  direction  of  the  indi- 
cations given  to  us  by  nature,  and  in  my  treatment  to 
place  the  power  in  their  relation  to  each  other  as  obviously 
intended. 

In  this  connection  and  for  the  sake  of  argument  we  will 
refer  to  Stevens,  page  199,  '  A  prism  with  its  base  down 
before  one  eye  is  equivalent  in  its  action  to  a  prism  with 
its  base  up  before  the  other,"  and  Hansell  of  Philadelphia 
advances  the  same  suggestion,  but  I  cannot  clearly  under- 


THE  MOVEMENTS  OF   THE  EYE. 


stand  this  theory,  which  implies  that  if  I  put  a  prism  of 
6°  over  my  right  eye,  with  the  base  down,  so  forcing  the 
eye  to  turn  upward  under  the  stimulation  for  fusion  by  the 
guiding  sensation,  how  then  will  there  be  any  innervation 
of  the  left  inferior  and  so  force  a  strain  on  the  opposing 
muscle  to  keep  the  image  of  the  candle  in  the  visual  line, 
when  there  is  no  stimulation,  in  that  eye,  from  the  guiding 
sensation  ? 

When  I  test  my  eyes  and  fix  them  on  the  candle  at 
twenty  feet  and  then  place  a  prism  over  one  eye,  base  up 
or  down,  the  position  of  the  candle  does  not  move,  nor 
tend  to  move,  unless  I  voluntarily  turn  both  eyes  upward, 
if  the  base  of  the  prism  is  down.  I  think  that  we  must 
have  the  guiding  sensation  to  stimulate  the  center  for 
fusion,  before  the  eye  will  move,  even  though  the  eyes 
act  together  in  their  associated  movements.  There  may 
be  exceptions  to  this  suggestion. 

All  this  can  be  proved,  if  we  place  Snellen's  test-type 
behind  the  candle  and  test  the  visual  power  in  each  eye, 
at  the  same  time.  If  the  eye  that  is  not  covered  by  a 
prism  deviates  even  one  or  two  degrees,  the  visual  power 
will  at  once  be  reduced,  then  as  long  as  the  visual  power 
is  up  to  the  standard  we  know  that  eye  must  be  placed 
so  that  the  visual  line  is  fixed  on  the  object  at  twenty  feet. 
If  there  should  be  any  movement  of  the  eye  not  covered, 
the  guiding  sensation  will  at  once  act  to  bring  the  image 
on  the  macula.  I  think  the  above  proposition  may  be 
proved  in  nearly  all  cases. 

In  a  paper  read  before  the  Clinical  Society  of  the  New 
York  Post-Graduate  School,  and  published  in  the  Post- 
Graduate  Journal  ior  May,  1896,  I  have  pointed  out  the 
indications  for  treatment,  that  we  may  find  as  we  proceed 
to  test  the  action  of  the  ocular  muscles  in  their  relation  to 
each  other.  The  literature  of  this  subject  shows  that 
nearly  all  of  our  prominent  writers  have  suggested  their 


28  STJRABISAfUS. 

own  methods  ;  as  Noyes  seems  to  depend  mostly  on  the 
prism  test,  Schiotz  gives  us  the  fusion  far-point  and  con- 
vergence near-point ;  Maddox,  the  rod-test  ;  Landolt,  the 
meter-angle,  while  Stevens,  having  taught  us  the  new 
nomenclature,  and  the  diagnosis  of  the  various  conditions 
of  heterophoria,  now  places  his  estimation  not  on  the  fu- 
sion power,  but  on  the  extent  of  the  field  of  fixation,  as 
shown  by  his  tropometer.  But  can  there  be  a  standard, 
such  as  we  have  universally  adopted  in  the  visual  power  of 
the  eyes  ?  And  as  we  use  the  glasses  to  test  that  visual 
power  may  we  not  use  the  prisms  to  estimate  the  relative 
power  of  the  ocular  muscles  and  to  find  any  existing  in- 
sufficiency, with  the  indications  for  treatment  ? 

If  so,  then  we  shall  only  consider  nature's  work  and  her 
needs  in  this  extremely  interesting  study  ;  that  the  guid- 
ing sensation  or  fusion  power  of  the  eye  is  the  one  and 
only  stimulation  by  which  the  binocular  visual  power  is 
controlled  and  that  nature  has  obviously,  in  her  anatomical 
construction  of  the  ocular  muscles,  pointed  out  to  us  the 
needs  and  necessities  of  the  eyes,  in  their  movements 
about  the  center  of  rotation,  in  reference  to  the  fusion 
power.  We  have  the  field  of  vision,  shown  by  the 
perimeter,  so,  similarly,  we  have  the  field  of  fixation,  rep- 
resented by  the  power  to  turn  the  eyes  on  the  center  of 
rotation,  and  lastly  the  field  of  fusion,  represented  by  the 
power  to  blend  the  rays  deviated  by  a  prism,  each  smaller 
in  extent  than  the  other,  and  each  in  inverse  proportion 
to  the  other  in  importance,  and  that  the  only  efficient  and 
reliable  tests  for  the  relative  power  of  the  ocular  muscles 
are  the  prism'and  that  of  the  tropometer.  Then  a  careful 
consideration  of  all  the  indications,  as  shown  by  these 
tests  will  lead  us  to  the  intelligent  and  successful  treat- 
ment for  the  restoration  of  the  balance  of  the  ocular  mus- 
cles, either  in  fixed  or  latent  squint. 

It  will  be  noted  that  in  my  explanation  of  the  move- 


THE  MOVEMENTS  OF  THE  EYE. 


29 


ments  of  the  eyeballs  I  have  not  considered  the  various 
planes  of  motion,  nor  that  of  the  axes  around  which  the 
eyeball  may  rotate  by  the  action  of  the  ocular  muscles. 
These  planes  and  axes  can  be  studied  in  our  text-books 
on  this  subject,  and.  I  do  not  consider  them  as  of  any 
special  importance  in  this  connection.  The  movement  of 
the  visual  line  will  pass  from  one  point  to  another  by  the 
shortest  and  quickest  route,  and  not  along  one  plane  and 
then  in  the  direction  of  the  other  —  in  other  words,  the 
eye  will  not  come  back  to  the  first  position  and  then  to 
the  required  point,  but  simply  passes  from  one  point  of 
regard  to  another,  turning  about  any  axis  relating  to 
these  two  points  that  passes  through  the  center  of  rota- 
tion. But  to  fully  understand  the  motions  of  the  eyes  by 
the  four  recti  we  must  consider  duo  principal  axes  of  rota- 
tion, the  vertical  and  the  horizontal,  with  their  respective 
planes  of  action,  in  reference  to  a  full  understanding  of 
the  actions  of  the  muscles  themselves.  These  four  mus- 
cles we  may  consider  as  acting  in  pairs,  or  as  one  muscle 
antagonistic  to  the  other.  The  internal  and  external 
recti  will  then  by  their  most  simple  action  move  the  eye- 
ball in  the  horizontal  plane,  turning  about  the  vertical 
axis,  and  the  superior  and  inferior  will  move  the  eyeball 
in  the  vertical  plane  about  the  horizontal  axis.  These 
are  the  two  simple  movements  of  the  eyeball,  from  which 
we  construct  the  terms  to  express  them,  but  as  the  eyeball 
rests  in  the  orbit  surrounded  "by  its  tissues  and  has 
no  fixed  attachment,  then  the  combined  action  of  any  of 
these  muscles  will  turn  the  eyeball  to  any  position  in  the 
field  of  fixation.  The  action  of  the  oblique  being  only 
concerned  in  torsion,  will  keep  the  two  vertical  planes  of 
the  eyes  parallel  to  each  other  in  all  positions.  Ellert 
says  :  "  The  production  of  motion  in  a  normal  eye  is  denied 
to  the  oblique  muscle,"  and  I  firmly  believe  in  that  state- 
ment. 


2o  STRABISMUS. 

Accepting  then  these  two  axes  of  rotation  and  these 
planes  of  motion,  it  is  essential  that  we  should  have  some 
terms  by  which  we  can  express  these  movements  of  the 
eyeballs  in  the  field  of  fixation  and  in  the  field  of  fusion. 
The  terminology  suggested  by  Ellert,  in  the  Journal  A. 
M.  A.,  October  18,  1902,  seems  to  me  will  meet  all  the 
requirements,  and  I  take  the  liberty  of  giving  these  terms 
in  full. 

MOVEMENTS   OF    THE    VISUAL    AXIS  : 

A.  Of  a  single  eye  (ductions)  : 

a.  Movements  of  the  V.  A.  outward  =  abduction. 

b.  Movements  of  the  V.  A.  inward  =  adduction. 

c.  Movements  of  the  V.  A.  upward  =  superduction. 

d.  Movements  of  the  V.  A.  downward  =  subduction. 

B.  Of  both  eyes  : 

1.  Associated  conjunctive  movements  (versions)  : 

a.  Movements  of  both  V.  A.  to  right  =  dextroversions. 

b.  Movements  of  both  V.  A.  to  left  =  levoversion. 

c.  Movements  of  both  V.  A.  upward  =  superversion. 
J.  Movements  of  both  V.  A.  downward  =  subversion. 

2.  Associated  disjunctive  movements  (vergences)  : 

a.  Inclining  the  V.  A.  toward  each  other  =  convergence. 

b.  Inclining  the  V.  A.  away  from  each  other  =  divergence. 

c.  Inclining  one  V.  A.  higher  than  the  other  =  superver- 

gence  (right  and  left). 

SPECIAL    TERMS    TO    DENOTE    THE    EXTENT    OF    ASSOCIATED    DISJUNC- 
TIVE   MOVEMENTS    AS    MEASURED    BY    PRISMS  : 

0.  Ability  to    overcome   prisms  bases   outward  =  prism- 
convergence. 

b.  Ability    to   overcome    prisms    bases    inward  =  prism- 

divergence. 

c.  Abrfity   to  overcome  prisms   bases   downward    or   up- 

ward =  prism-supervergence  (right  and  left). 

Ellert  adds  to  this, 

SPECIAL    TERMS    TO    DENOTE    THE    EXTENT    OF    TORSION  : 

a.  Movement  of  the  vertical  axis  outward  =  extorsion. 

b.  Movement  of  the  vertical  axis  inward  =  intorsion. 


THE   MOVEMENTS  OF  THE  EYE. 


These  terms  apply  to  the  movements  of  the  eyeball 
about  the  sagittal  axis,  and  depend  upon  the  action  of  the 
oblique  muscles. 

Savage  has  suggested  the  term  cyclophoria  (plus  and 
minus),  and  cyclotropia  (plus  and  minus).  I  can  see  no 
reason  why  these  conditions  may  not  exist,  as  we  may 
have  a  weakness  of  the  oblique  muscles,  the  same  as  that 
of  the  recti,  but  in  the  last  classification  if  we  have  a 
malposition  of  the  vertical  plane,  it  must  be  due  to  a 
pathological  condition  (paralysis)  when  present.  These 
cases  are  very  rare. 

In  closing  this  discussion  of  the  action  of  the  muscles 
of  the  eyeball,  we  must  not  consider  the  eye  as  a  rubber 
ball  and  the  axes  as  a  number  of  knitting  needles.  That  is 
man's  mechanical  method,  but  let  us  study  the  movements 
of  the  eye  and  the  direction  of  the  visual  line  from  the 
standpoint  of  nature,  even  if  that  is  an  "  every-day  affair,  " 
unfortunately  not  referred  to  in  our  text-books.  Then 
we  shall  simply  note  that  the  recti  muscles  control  the 
movement  of  the  eyes  in  the  field  of  version  by  their 
voluntary  action,  and  in  the  field  of  duction  by  their 
involuntary  action,  and,  lastly,  that  "  the  obliques  must 
keep  the  vertical  axes  parallel  with  each  other  and  with 
the  median  plane  of  the  head  when  in  the  first  position." 


CHAPTER  III. 

CLASSIFICATION    OF    SQUINT. 

IT  has  been  well  established  that  we  should  have  some 
terms  to  express  the  various  conditions  of  squint,  either 
latent  or  fixed,  that  may  be  simple  and  easily  understood, 
and  at  the  same  time  convey  all  the  necessary  information 
as  to  the  deviation  of  the  visual  lines,  or  the  tendency  to 
that  condition.  I  am  more  than  convinced  that  we  have 
no  distinct  dividing  line  between  the  two  conditions  as 
far  as  a  scientific  examination  may  reveal,  and  as  I  believe 
we  have  only  one  true  underlying  cause  as  the  funda- 
mental starting-point  of  all  squint,  it  becomes  only  one  of 
degree,  from  that  of  the  slightest  tendency  to  a  deviation 
of  the  visual  lines  when  in  the  first  position  of  the  eye,  to 
that  of  the  most  extreme  fixed  deviation  in  any  direction ; 
but,  objectively,  there  does  seem  to  be  a  distinct  dividing 
line  on  each  side  of  which  we  may  place,  first,  those  cases 
in  which  we  have  a  tendency  to  deviation  —  latent  squint ; 
and  second,  those  cases  in  which  we  have  a  constant 
deviation  —  fixed  squint. 

Hence  it  is  very  appropriate  that  we  shall  have  some 
terms  that  will  indicate  at  once  these  two  grand  divisions 
writh  all  their  various  complications,  from  the  slightest 
heterophoria  to  that  of  fixed  squint.  In  this  classification 
I  shall  use  the  first  position  of  the  eyes  as  a  starting- 
point,  which,  as  I  understand  it,  will  be  fully  discussed 
under  the  condition  of  exophoria.  From  this  position 
we  may  then  consider  not  only  the  deviation  of  one 
visual  line  from  that  of  the  other,  but  also  any  deviation 
of  both  visual  lines  together.  I  do  not  know  of  a  better 


CLASSIFICATION  OF  SQUINT.  33 

classification,  and  one  that  has  been  almost  universally 
adopted,  than  that  of  Stevens,  in  which  he  has  considered 
almost  every  possible  deviation  that  may  occur  in  the 
position  of  the  visual  line.  Hence  we  have  the  following 
terms  : 

Orthophoria  =  parallelism  of  the  visual  lines,  no  tendency  to 

deviation. 
Heterophoria  =  the  tendency  to  deviation  from  parallelism 

of  the  visual  lines. 
Hyperphoria  =  a  tendency  of   one  visual    axis   above   the 

other  (right  or  left). 
Hypophoria  =  a  tendency  of    one    visual  axis    below    the 

other  (right  or  left). 

Esophoria=a  tendency  of  the  visual  axes  inward. 
Exophoria  =  a  tendency  of  the  visual  axes  outward. 

These  terms  may  also  be  combined  to  express  any 
tendency  of  the  visual  axes  in  more  than  one  direction,  as 

Hyper-esophoria  =  a  tendency  upward  and  inward. 
Hypo-esophoria  =  a  tendency  downward  and  inward. 
Hyper-exophoria  =  a  tendency  upward  and  outward. 
Hypo-exophoria  =  a  tendency  downward  and  outward. 

We  have  here  distinct  and  clear  expressions  in  a  single 
term  that  will  indicate  any  and  all  deviations  of  the  visual 
axis  from  that  of  the  first  position,  modified  only  by  the 
degree  of  deviation  as  shown  in  the  examination.  Sim- 
ilarly, we  have  below  the  terms  that  will  denote  a  fixed 
condition,  simply  one  of  degree,  from  that  of  the  first 
series  of  terms : 

Esotropia  =  deviation  of  the  visual  axes  inward,  or  conver- 
gent squint. 

Exotropia  =  deviation  of  the  visual  axes  outward,  or  diver- 
gent squint. 

Hypertropia  =  deviation  of  one  visual  axis  above  the  other, 
upward  squint. 

Hypotropia  =  deviation  of  one  visual  axis  below  the  other, 
downward  squint. 


34 


STRABISMUS. 


These  terms  may  also  be  combined,  as 

Hyper-esotropia  =  upward  and  inward. 
Hyper-exotropia  =  upward  and  outward. 
Hypo-esotropia  =  downward  and  inward. 
Hypo-exotropia  =  downward  and  outward. 

These  various  conditions  may  exist  in  any  degree,  and 
in  fact,  it  seems  to  me  that  all  squint  of  whatever  variety 
is  simply  one  of  degree  rather  than  one  of  kind,  as  in  one 
case  the  deviation  is  obvious  and  more  or  less  fixed,  in 
the  other  the  deviation  can  only  be  detected  by  the  most 
careful  examination  by  the  present  methods.  Again, 
even  these  two  conditions  show  many  different  degrees, 
as  in  fixed  squint  the  deviation  of  the  visual  lines  may 
be  from  that  of  the  slightest  to  that  of  the  greatest  degree 
in  any  direction. 

Stevens  has  also  given  us  other  expressions  that  will  in- 
dicate the  deviation  of  the  visual  lines  together,  as  one 
case  may  have  a  tendency  to  deviation  of  both  visual  lines 
above  the  plane  of  regard,  and  another  below  it.  Hence 
we  have  these  terms  : 

Euphoria  =  33°  up  and  50°  down,  or  normal  rotation. 
Anaphoria  =  a  tendency  of  both  visual  axes  upward. 
Kataphoria  =  a  tendency  of  both  visual  axes  downward. 
Anatropia  =  a  deviation  of  both  visual  axes  upward. 
Katatropia=a  deviation  of  both  visual  axes  downward. 
\ 

To  these  conditions  I  would  add  certain  tendencies  of 
the  visual  axes  to  turn  to  the  right  or  left,  in  which,  by 
the  examination,  we  find  a  weakness  of  one  internus  and 
one  externus,  giving  a  tendency  to  look  to  the  right  or 
left.  I  do  not  propose  to  suggest  any  special  term  for  this 
condition,  but  as  I  have  met  some  cases,  prefer  to  note  it 
in  this  classification  and  to  explain  it  under  the  subject  of 
Heterophoria. 

Lastly,  to  make  this   classification   complete,  although 


CLASSIFICATION  OF  SQUINT.  35 

somewhat  beyond  the  scope  of  this  monograph,  we  have 
the  condition  in  which  there  is  a  tendency  to  the  deviation 
of  the  vertical  meridian  of  one  eye  from  that  of  the  median 
vertical  plane  of  the  head : 

Plus  Cyclophoria  =  a  tendency  of  the  vertical  axis  from  the  median 

plane  of  the  head. 

Minus  Cyclophoria  =  a  tendency  of  the  vertical  axis  toward  the  me- 
dian plane  of  the  head. 

These  terms  are  here  used  for  the  purposes  of  uni- 
formity, as  Stevens'  designation  is  respectively,  "  Plus 
declination  and  minus  declination,"  which  seem  to  me 
much  more  appropriate,  and  may  be  simply  considered  as 
complications  of  squint.  Consequently  they  will  not  be 
fully  or  separately  discussed,  except  so  far  as  they  may 
complicate  any  deviation  of  the  visual  line. 


CHAPTER  IV. 

ESOPHORIA,    OR    LATEKT    CONVERGENT    SQUINT. 

"  If  Esophoria  be  regarded  as  latent,  then  Convergent  Squint  may  be  considered 
as  an  Esophoria  which  has  become  manifest  and  immutable  strabismus." — Campbell. 

OPHTHALMOLOGISTS  have  not  agreed  upon  the  exact 
method  of  examination  that  we  should  pursue  in  the  esti- 
mation of  an  imbalance  of  the  ocular  muscles,  nor  are  the 
results  of  our  final  work  the  same  in  all  cases,  even  though 
•we  may  be  much  more  exact  now  in  the  estimation  of  the 
refractive  apparatus.  This  is  particularly  so  in  the  estima- 
tion of  the  motility  of  the  eyes,  in  other  words  the  power  of 
the  eyes  to  move  in  the  fields  of  fusion  and  version.  The 
same  difference  of  opinion  seems  to  exist  in  the  other 
branches  of  our  profession  as  I  believe  it  is  not  fully  settled 
yet,  whether  antitoxin  is  a  positive  specific  for  diphtheria, 
and  as  to  the  right  and  proper  time  to  operate  in  all  cases 
of  appendicitis.  Medicine  has  not  yet  reached  that  stage 
—  nor  do  I  think  it  ever  will  —  when  we  can  make  the  con- 
dition of  all  our  cases  an  exact  science  by  which  we  can 
tell  just  what  will  be  the  final  result.  We  must  deal  with 
the  personal  equation  of  our  patients,  an  extremely  vary- 
ing quantity.  If  others  may  have  these  diverse  opin- 
ions, so  do  the  ophthalmologists  hold  the  same  in  reference 
to  the  subject  of  the  motility  of  the  eyes.  Some  may 
believe  that  latent  squint  does  not  exist,  or  if  so,  that  it 
simply  requires  the  use  of  glasses  ;  others,  that  nearly  all 
cases  of  asthenopia  present  this  condition  and  that  the 
majority  of  cases  will  require  one  or  more  operations. 

For  my  own  views  and  from  my  experience  I  must  say 
I  am  inclined  to  take  a  conservative  course,  simply 


ESOPHOKIA.  77 

^  / 

endeavoring    to    correct    the    refractive    error,    whatever 

o 

that  may  be,  and  then  to  place  the  muscular  apparatus,  if 
necessary,  in  that  condition  of  equilibrium  that  nature 
obviously  intended.  Having  done  this  and  the  patient 
finds  no  relief  I  can  justly  feel  that  the  eyes  are  not  at 
fault.  My  methods  of  examination  and  conclusions  may 
not  be  correct  —  as  they  have  not  been  approved  of  by 
many  other  examiners  —  but  they  have  at  least  the 
advantage  of  having  been  used  for  many  years  by  myself 
with  continued  satisfaction. 

Now  there  is  much  diversity  of  opinion  in  reference  to 
the  muscular  equilibrium  of  the  eyes.  When  there  is  an 
absence  of  this  condition  the  writers  state  that  the  fundi- 
mental  cause  is  hypermetropia,  and  then  proceed  to 
explain  the  relation  between  cause  and  effect,  or,  we  may 
say  the  physiological  connection  between  accommodation 
and  convergence,  to  account  for  it  ;  but  they  fail  to  point 
out  why  the  same  condition  may  and  does  exist  when  the 
refraction  of  the  eye  is  found  to  be  myopic.  So  we  find 
this  latent  tendency  with  myopia  described  in  "  vague 
terms  "  as  ciliary  spasm  —  a  rare  condition  in  myopia  —  or 
we  find  no  explanation  at  all  ;  or,  again,  it  is  so  described 
that  the  reader  cannot  decide  what  is  the  chief  or  primal 
cause  of  the  condition  and  he  is  entirely  at  sea  as  to  what 
procedure  he  shall  adopt  when  he  fails  to  correct  and 
relieve  his  cases  with  the  use  of  glasses,  or  by  the  method 
of  exercising  the  muscles,  so  frequently  suggested.  It 
is  for  these  reasons  that  I  wish  to  offer  some  suggestions, 
or  methods,  based  on  my  own  experience,  and  by  which  I 
have  almost  invariably  given  relief. 

At  one  time  I  also  held  the  opinion  that  hypermetropia 
was  the  cause  of  esophoria  and  convergent  squint,  but, 
when  I  noticed  the  vast  number  of  hyperopes  that  had  no 
tendency  to  these  conditions  and  that  the  greater  the 
hypermetropia  the  less  did  I  find  this  inability  to  keep 


38  STRABISMUS. 

the  visual  lines  fixed,  then  I  began  to  doubt  my  former 
opinions.  Furthermore,  when  I  also  found  this  condition 
associated  with  myopia  and  even  emmetropia,  I  felt  com- 
pelled to  discard  the  theory  of  the  connection  between 
accommodation  and  convergence  as  the  true  cause  and  to 
look  for  other  reasons  that  would  meet  all  the  indications. 
This  can  be  found  in  the  field  of  fusion  or  the  desire  for 
single  vision,  and  in  the  field  of  version  or  the  rotation  of 
the  eyes.  The  desire  for  fusion  must  be  controlled  by  a 
different  part  of  the  brain  from  that  of  fixation,  in  other 
words,  one  is  automatic  and  the  other  is  control. 

The  power  of  an  eye  muscle  to  act  according  to  its 
physiological  function  is  shown,  first,  by  the  ability  of  the 
individual  to  do  certain  acts  by  the  process  of  muscular 
contraction,  stimulated  by  the  innervation  and  controlled 
by  the  will-power  and,  second,  the  ability  to  turn  the 
eyes,  one  independent  of  the  other,  under  the  stimulation 
of  the  desire  for  single  or  binocular  vision.  This  latter 
power  is  the  fusion  force,  and  is  not  under  the  control  of 
the  will-power  of  the  individual.  Under  these  conditions 
we  find  that  the  eyes  can  turn  to  all  parts  of  the  field  of 
fixation  in  nearly  the  same  degrees  of  the  arc  of  a  circle, 
while,  on  the  other  hand,  the  eye  will  also  move  to  a  cer- 
tain extent  and  within  a  certain  field  {fusioti}  not  by  the 
will-power,  but  by  that  of  the  muscular  apparatus,  under 
the  stimulation  of  the  center  for  fusion,  due  to  the  desire 
for  single  images  or  that  the  images  may  be  on  corre- 
sponding parts  of  the  retina.  This  power  of  the  muscular 
apparatus  seems  to  be  limited  within  a  certain  field,  and 
we  find  this  fusion  force  acting  in  the  same  way  when  the 
eyes  are  directed  to  the  different  parts  of  the  field  of  fixa- 
tion. Hence  the  ability  to  fuse  these  images  must  be 
controlled  by  a  special  center,  and  the  extent  to  which  the 
eyes  can  be  turned  to  produce  this  fusion  must  represent 
the  power  of  the  muscles  to  turn  the  eyes.  I  can  see  no 


ESOPHORIA. 


39 


other  way  to  consider  the  action  of  the  ocular  muscles 
than  their  individual  power  to  turn  the  eyes  under  certain 
conditions.  Moreover,  I  cannot  consider  this  force  as 
innervation,  nor  that  there  should  be  more  stimulation  to 
one  muscle  than  to  the  other,  since  the  size  and  the 
insertion  of  all  the  straight  muscles  seem  to  point  to  the 
fact  that  one  muscle  must  have  more  power  than  the  other 
for  some  special  purpose  ;  or,  in  other  words,  exert  a 
greater  power  to  turn  the  eye  under  the  stimulation  of  the 
fusion  force. 

The  physiological  act  of  turning  the  eyes  in  all  direc- 
tions within  certain  limits  requires  very  little  force,  as  is 
well  shown  by  the  action  of  the  interni  and  the  superior 
recti  muscles,  for  the  eyes  will  turn  upward  as  well  as 
inward,  and  yet  the  size  and  the  insertion  of  the  interni 
clearly  indicate  that  these  muscles  must  have  been 
intended  to  exert  a  greater  power  in  some  way.  May  we 
not  also  accept  the  supposition  that  nature  arranged  this 
muscular  force,  not  only  to  perform  the  simple  act  of 
turning  the  eyes,  but  that  they  might  also  conform  to 
all  the  requirements  of  the  more  important  functions, 
namely,  that  of  binocular  vision  and  convergence,  as  con- 
trolled by  the  fusion  force  of  the  eyes  ?  Do  not  the  daily 
needs  of  vision  confirm  all  this  ?  It  is  in  the  act  of  single 
vision,  both  for  the  distant  and  near  points,  that  we  find 
the  eyes  constantly  called  upon  to  keep  the  visual  lines 
fixed  on  an  object,  while  at  the  same  time  the  eyes  are 
moved  to  different  parts  of  the  field  of  fixation.  Upon 
this  supposition  I  cannot  see  what  influence  innervation, 
the  position  of  rest,  or  the  natural  elasticity  of  the  externi, 
have  to  do  with  the  fusion  of  the  images  on  the  retina.  If 
we  accept  this  reasoning  and  believe  that  certain  muscles 
have  a  greater  power  to  turn  the  eyes  under  certain  stim- 
ulation, then  we  should  have  some  test  sufficiently  reliable 
and  exact  which  will  meet  the  requirements  and  indicate 


STRABISMUS. 


to  us  what  is  the  actual  power  of  these  muscles  to  turn 
the  eyes  under  certain  conditions.  I  have  used  and  tried 
faithfully  all  the  various  tests  as  suggested  for  this  pur- 
pose, such  as  the  phorometer,  Maddox  rods,  etc.,  but  I 
can  find  no  test  so  reliable  and  so  clearly  indicative  of  the 
power  of  these  muscles,  as  the  old  and  simple  prism  test. 
We  turn  the  eyes  in  the  field  of  fixation  under  the  stimu- 
lation of  the  will,  simply  because  we  wish  to  see  in  certain 
directions.  This  is  the  conscious  part  of  the  action  of  the 
eye-muscle ;  but  having  performed  this  act  we  now  call 
into  action  the  unconscious  part,  in  which  the  eyes  must 
adjust  the  visual  line  according  to  the  direction  of  the 
rays  of  light  as  they  pass  through  the  dioptric  media.  If 
these  rays  of  light  are  deviated  from  their  natural  path 
the  eyes  will  turn  on  the  center  of  rotation  to  meet  the  de- 
viated rays  until  the  visual  line  will  be  parallel  with  them 
and  the  principal  axial  ray  falls  upon  the  macula.  If 
I  deviate  the  rays  passing  into  one  eye  20°  from  a  direct 
line,  then  to  have  single  vision  there  must  be  sufficient 
muscular  power  to  turn  the  eye  in  the  direction  of  the 
deviated  ray,  namely,  20°  of  the  arc,  and  if  we  cannot  fuse 
the  images  then  we  do  not  have  sufficient  muscular  power 
in  the  muscle  so  tested.  Therefore,  the  strongest  prism 
that  will  deviate  the  rays  and  yet  have  single  vision 
remain  must  indicate  the  power  of  that  muscle  to  turn 
the  eye.  Now,  if  the  deviation  by  a  prism  represents  the 
power  of  the  eyes  to  turn  on  the  center  of  rotation  under 
the  stimulation  of  the  fusion  force  (ductiori)  what  do  we 
find  is  the  relative  force  or  power  of  these  straight  mus- 
cles ?  Evidently  we  may  have  some  standard  of  compar- 
ison, in  the  same  way  and  for  the  same  reason  that  we 
have  a  standard  for  the  acuity  of  the  vision. 

First,  the  power  of  the  externi  to  turn  the  eyeball  out- 
ward must  be  considered.  Let  me  state  at  once  that  I  do 
not  consider  this  power  as  acting  from  the  position  of  ex- 


ESOPHORIA. 


treme  convergence  or  any  point  midway  between  that  of 
extreme  convergence  and  divergence,  as  has  been  su^r- 

o  <_>  o 

gested  by  some  writers,  but  as  starting  from  the  usual  first 
position  of  the  eyes,  in  which  they  are  directed  toward  a 
point  about  twenty  feet  distant  and  about  15°  below  the 
horizon.  Second,  the  power  of  the  eyes  to  move  under 
the  stimulation  of  that  unconscious  force  or  duction,  as 
shown  by  the  prism  test,  must  be  measured  in  the  remain- 
ing parts  of  the  field.  We  should  find  the  outward  move- 
ment or  abduction  about  6°.  Any  decided  variation  from 
this  may  indicate  some  latent  squint.  The  inward  move- 
ment or  adduction  is  about  24°  ;  the  upward  movement 
or  sursumduction  about  2°,  and  the  downward  movement 
or  deorsumduction  about  3  °,  or  somewhat  greater  than  the 
upward  power.  These  movements  are  indicated  by  the 
relative  size  and  insertion  of  the  straight  muscles,  and  very 
beautifully  represents  the  power  of  the  muscles  to  turn  the 
eyes  under  the  desire  for  single  vision,  while  the  slightest 
failure  of  this  muscular  power  may  result  in  diplopia. 
Now,  in  the  above  standard  we  shall  find  a  certain  relation 
in  the  power  of  these  muscles,  one  to  the  other,  as  the  in- 
terni  are  the  most  powerful ;  next  the  externi ;  then  the 
inferior,  and,  lastly,  the  superior,  each  one  having  a  certain 
ratio  to  the  other.  When  this  is  constant  —  no  matter  what 
the  actual  power  may  be  —  we  will  not,  as  a  rule,  find  much 
if  any  muscular  asthenopia  or  tendency  to  latent  squint. 
Having,  then,  this  standard  by  which  to  compare  the  re- 
sults of  our  tests  of  the  muscular  balance  as  found  in  our 
patients,  what  will  be  the  indications  of  the  condition  that 
is  the  subject  of  this  chapter?  At  once  we  note  that  the 
power  of  the  interni  is  far  greater  than  that  indicated  by 
our  standard,  or  vice  versa,  that  the  power  of  the  externi 
is  too  low,  so  that  under  the  stimulation  of  the  fusion  force 
the  power  of  abduction  is  not  great  enough  to  control  the 
position  of  the  eyes  except  by  the  excessive  stimulation  of 


42 


STRABISMUS. 


the  extern!  to  keep  the  visual  lines  fixed.  These  patients 
present  the  usual  train  of  symptoms,  chiefly  pain  in  the 
head,  radiating  backward  toward  the  neck,  and  a  pulling 
sensation  about  the  eyes.  Latent  squint  of  the  conver- 
gent class  is  sometimes  described  as  spasmodic  action  of 
the  interni,  and  in  some  cases  our  tests  show  this  condi- 
tion ;  but  even  if  it  is  spasmodic  action  of  that  muscle  it 
still  indicates  too  much  power,  and  should  and  can  be  con- 
trolled by  proper  and  suitable  means.  Some  of.  my  best 
cases  have  shown  this  condition,  as  I  have  noticed  a  pe- 
culiar change  in  the  response  of  the  externi  to  the  prism 
test,  in  which  there  seems  to  be  a  decided  loss  of  power 
after  we  have  tested  the  adduction.  This  is  shown  by  the 
prism  test  as  well  as  by  the  phorometer  or  the  Maddox 
rod.  If  we  test  the  power  of  abduction  we  find  a  certain 
ability  to  turn  the  eye  outward  under  the  stimulation  of 
the  fusion  force,  that  as  measured  by  the  prisms  may  be 
as  high  as  6°.  Now,  testing  the  adduction  in  the  same 
way  we  have  20°  or  more,  showing  a  fairly  good  balance 
between  adduction  and  abduction  ;  but  if  we  go  back  and 
again  test  the  power  of  abduction  we  will  find  that  it  has 
become  reduced  to  i  °  or  2°,  or  possibly  we  will  have  ho- 
monymous  diplopia  —  particularly  if  we  place  a  red  glass 
before  one  eye  —  which  may  persist  for  some  time  before 
the  balance  again  adjusts  itself,  and  we  have  single  vision. 
I  have  considered  this  a  very  valuable  test  to  develop  the 
tendency  of  the  eyes  to  t-urn  inward,  and  while  it  may  be 
due  to  some  spasmodic  action  of  the  interni,  yet  I  consider 
it  one  of  the  best  indications  for  an  operation.  This  con- 
dition of  the  externi  or  weakness  of  the  muscle  will  also 
be  shown  in  the  test  of  the  field  of  version  by  the  tro- 
pometer.  In  this  field  we  will  find  the  voluntary  power  to 
turn  the  eye  outward  much  less  than  normal,  while  the  in- 
ward rotation  will  probably  be  greater. 

Having  found  the  conditions  of  latent  squint,  conver- 


ESOPHORIA. 


43 


gent,  our  method  of  treatment  for  its  correction  is,  first, 
the  use  of  suitable  glasses  to  correct  any  existing  refrac- 
tive errors.  This  failing,  the  combination  of  prisms  with 
the  glasses  may  be  tried ;  then  possibly  tenotomy  of  the 
interni ;  but  best  of  all,  in  my  opinion,  is  the  operation 
for  shortening  the  externus  with  a  catgut  suture,  thereby 
increasing  its  power  to  turn  the  visual  line  outward  and  at 
the  same  time  avoiding  all  danger  of  an  overcorrection. 
It  is  to  show  the  results  of  this  operation  of  shortening 
the  ocular  muscles  for  the  correction  of  this  condition  that 
I  present  these  cases  from  my  private  case-book,  and  also 
to  demonstrate  the  utility  of  this  standard  test : 

CASE  1484. — Hy.  with  Ah.  glasses  four  years.  ¥=20/20,  Ad.  20°, 
Ab.  2°  (ratio  i  to  10).  Operation:  Shortening  of  Ext.  Rect. 
Result,  Ad.  15°,  Ab.  4°  (ratio  i  to  4). 

CASE  1755. — Hy.  with  Ah.  glasses  several  years  ;  no  relief,  V= 
20/15,  Ad.  25°,  Ab.  2°;  after  testing  Interni,  Ab.  o  .  Was  told  by 
another  oculist  that  operation  would  do  no  good.  Operation  was 
shortening  of  Left  Externus.  Result,  Ad.  15°,  Ab.  5°.  Two  years 
later  reports  can  use  the  eyes  all  that  is  needed  with  comfort. 

CASE  1829. — Ah.  glasses.  ¥=20/15,  Ad.  30°,  Ab.  4°.  Operation  : 
Shortening  of  Left  Ext.  Rect.  One  year  after  is  so  much  improved 
that  she  returns  and  asks  for  an  operation  on  the  other  eye,  and  I 
shortened  the  Right  Ext.  Rect.  in  the  same  way,  with  this  final  re- 
sult, Ad.  20°,  Ab.  5°.  Can  now  use  the  eyes  with  comfort. 

CASE  1839. — Hy.  with  Ah.,  using  glasses  ;  no  improvement.  V. 
20/15,  Ad.  15°,  Ab.  o°.  Operation  :  Shortening  of  Left  Ext.  Rect. 
Result,  Ad.  16°,  Ab.  3°. 

CASE  1909. — My.  with  Am.,  using  glasses.  ¥=20/15,  Ad.  20°,  Ab. 
4°.  After  testing  Interni,  Ab.  o°.  Operation  :  Shortening  of  Left 
Ext.  Rect.  Final  result,  Ad.  15°,  Ab.  6°.  Two  years  after  reports 
no  pain  or  asthenopia. 

CASE  1942. — Hy.  with  Ah.,  using  glasses.  ¥=20/20,  Ad.  10°,  Ab. 
i°.  Operation:  Shortening  Left  Ext.  Rect.  One  year  after  has 
Ad.  12°,  Ab.  4°. 

CASE  1977. — Hy.,  using  glasses.  ¥  =  20/15,  Ad.  25°,  Ab.  o°. 
Operation  :  Left  Ext.  Rect.  Final  result,  Ad.  20°,  Ab.  6°. 

CASE   2051. — Ah.,    using    glasses.       ¥=20/15,    Ad.   30°,    Ab.   6°. 


44 


STRABISMUS. 


After  testing  Interni,  Ab.  falls  to  o°.  Operation  on  Ext.  Rect. 
Final  result,  Ad.  20°,  Ab.  6°,  six  months  after  operation. 

CASE  2065. — My.,  using  glasses.  ¥=20/15,  Ad.  30°,  Ab.  3°.  Oper- 
ation, Ext.  Rect.  Final  result,  Ad.  24°,  Ad.  6°. 

CASE  2292. — Hy.  with  Ah.  using  glasses.  O.  D.— 20/20,  O. 
S.=2o/4o,  Ad.  30  °,  Ab.  3  °.  Operation.  Final  result,  Ad.  20  °,  Ab.  6  °. 

CASE  2371. — Ky.  with  Ah.,  using  glasses.  ¥=20/20,  Ad,  25  °,  Ab. 
6°.  After  testing  Interni,  Ab.  o°.  Operation:  Shortening  Right 
Ext,  Rect.  One  year  after,  Ad.  25°,  Ab.  6°,  permanent. 

CASE  2385, — Ah.  ax.  180°,  using  glasses.  ¥=20/15,  Ad.  20°,  Ab. 
4°.  After  testing  Interni,  Ab.  o°.  Operation:  Shortening.  Four 
months  after,  Ad.  15  °,  Ab.  4°. 

CASE  2088. — Ah.,  using  glasses.  ¥=20/15.  Better  with  glasses, 
but  not  relieved.  Ad,  20°,  Ab.  i°,  and  homonymous  diplopia  after 
testing  Interni.  Operation  :  Shortening;  Ab.  4°.,  much  better. 

CASE  2459. — Ah.,  using  glasses.  ¥=20/15,  Ad.  25°>  Ab.  2°>  ^a^s 
to  o°,  with  homonymous  diplopia  after  testing  Interni.  Operation  : 
Shortening.  Six  months  after,  Ad.  15°,  Ab.  5°. 

CASE  2621. — Ah.  ¥=20/15.  Glasses  do  not  stop  asthenopia.  Ad. 
20°,  Ab.  i°.  Operation  :  Shortening,  Result,  Ad.  15  °,  Ab.  4°. 

CASE  2571. — Ah.  ax.  180°.  ¥=20/15.  Glasses  relieve  at  first,  then 
fail.  Ad.  15°,  Ab.  i°;  homonymous  diplopia  with  red  glass.  Opera- 
tion :  Shortening.  Result,  Ad.  15°,  Ab,  5°;  complete  relief. 

These  cases  usually  present  the  history  that  the  patients 
cannot  read  ;  the  eyes  are  painful ;  headaches,  frontal  and 
usually  extending  backward,  are  experienced,  and  there 
may  be  car-sickness,  nausea,  etc.  I  have  presented  the 
histories  of  these  cases  of  esophoria,  or  latent  convergent 
squint,  in  the  simplest  condensed  form  possible,  noting 
the  refraction,  glasses  worn  without  relief,  acuity  of  vision, 
the  muscle  imbalance,  the  muscle  operated  upon,  and  the 
final  result.  They  all  seem  to  show  a  want  of  power  in 
the  external  rectt  muscles,  a  tendency  for  the  eyes  to  turn 
inward,  and,  finally,  show  an  improvement  in  that  power 
by  the  muscle  balance  after  the  operation.  Now,  I 
would  state  that  the  same  operation  was  performed  in 
each  case,  namely,  that  of  shortening  the  muscle  by  the 
insertion  of  the  catgut  suture  by  a  simple  method  so  as 


ESOPHORIA. 


45 


to  form  a  "tuck  "  at  the  insertion  of  the  tendon  into  the 
sclera,  and  allowing  the  suture  to  be  absorbed.  It  is 
fully  detailed  in  the  article  on  operations. 


CONDENSED  HISTORIES  OF  CASES  OF  ESOPHORIA. 


Vision;  Age;     Refrac.    Add.  Abd.     Tropomet.             Operation,                     Esoph.     Add.  Abd.        Remarks 
first     ex.         in  out          tuck.              ten.  .                 deg.        last    ex.           and  after 
No.                                                                                           ext.                 int.                  before                                  effects 
Rt.  Lt.                                                                                                                                    oper 

IIS    15 

50 

Ah. 

6C 

6  - 

both 

'20  :   8% 

2 

20 

20 

35 

Ah. 

both 

8°   to  2515=    5°,  almost  squint 

3 

'5 

15,36 

My.wAm. 

5°  c 

I  = 

L. 

4°        25=  6°,  good  9  years 

4  15 

15 

3° 

Hy. 

r  O 

L. 

4=       20=  3°, 

5  20 

20 

'7 

Am. 

20  c 

j  : 

Tuck  &  Ten.  R.  Sup. 

4°  Hy.  4  20°   6°, 

6 

20 

20 

20 

Am. 

10° 

I  ° 

R. 

2=       10=  3°, 

exer.  no  use 

7 

20 

30 

38 

Ah. 

12° 

o- 

55°  -40° 

L. 

&  L.  Sup. 

6=       12°  4°, 

had  prisms 

8 

>5 

15 

26 

Ah. 

25  = 

l  o 

50°  -40  = 

R. 

Reports 

no  imp.  in  svmp. 

9 

'5 

15 

3' 

Hy.wAh. 

15° 

3° 

5o°-45° 

R. 

2°       15°  4*, 

50=  —  50  3 

10 

'5 

15 

4' 

Ah. 

15  = 

2  - 

50°  -40° 

L. 

20°  5°, 

45°—  45° 

II 

20 

20 

33 

My.wAm. 

60  ' 

G  - 

55°-45° 

L. 

6°       50  =  15°, 

good  i  year 

12 

'5 

15 

43 

Ah. 

•5° 

2° 

5°o~4°n 

L. 

&  L.  Sup. 

3°       IS'  SS 

.  .  O         .  ,  0 

45  „  —  4j  , 

>  3 

15 

34 

Ah. 

12  ° 

2° 

5°°-400 

R. 

3  =       124", 

40  -  —  40  - 

'4 

15 

15 

-4 

Hy.wAh. 

5°     25  ° 

L. 

L. 

10  = 

5°"—  35° 

15 

'5 

15 

45 

Hy. 

'5° 

4C 

50°  -40° 

L. 

L. 

2°       15=   5°. 

40  -  —  40 

16 

'5 

1543 

Hy. 

20  o 

3  : 

45c-35° 

L. 

L. 

5=       16°  6°. 

40°—  40° 

17 

rfc 

'9 

20 

«5 

'5 

20  28 

15  20 
1518 

Hy. 
Ah. 
Ah. 

'5 

10° 

ic 

2° 

L. 
L. 
R. 

6° 

10° 

20-   6  =  , 

10°  3  =  , 

good  2  years 

20 

'5 

15 

Ah. 

40  c 

4  - 

both 

4°       35°   «=, 

21 

IS 

15 

Ah. 

3°; 

41 

L. 

sl     20!  5°. 

good  4  years 

22 

'5 

!5!40 

Hy. 

250 

2° 

R. 

3° 

15-  o°, 

..0          .rO 

45    —  45 

^3 

20 

20  23 

Hy. 

'5 

0  ' 

L. 

4° 

I5o    3  =  ' 

24 

20 

20:36 

Hy.wAh. 

I2C 

1° 

L. 

12°    40, 

25 

40 

200  29 

My.  &  Hy. 

20  ° 

1° 

Hyper.  I  ' 

L. 

8° 

20°  5°, 

26 

20 

20  51 

Ah. 

30: 

4: 

both 

20°  5°, 

27 

20 

2O  24 

Hy. 

'So 

I  ° 

Hyper.  4  c 

L. 

4° 

20°    6°, 

2S 

20 

15  3S 

Mv.wAm. 

20° 

O  ' 

L. 

15=  8°, 

29 

15 

15 

32 

'Ah. 

30° 

2° 

R. 

10  = 

28°  8°, 

3° 

'5 

«547 

My. 

3°c 

4: 

L. 

24°  6°, 

31 

'5 

15  20 

Ah. 

2O 

2° 

Hyper.  2  ° 

L. 

•5  0 

*5°  4°, 

15    1520 

Ah. 

20° 

oc 

L. 

15  °  3  °» 

33 

40 

20:24 

Ah. 

25° 

2"- 

Hyper.  3° 

L. 

4° 

25°  8°, 

34 

'5 

1534 

Ah. 

15° 

Z 

L. 

6  = 

12=  3°, 

**  O  ' 

Petit.   Mai. 

35 

15    1528 

Ah. 

25° 

L. 

6  = 

rs°  So. 

36 

20      1534 

Hy.  wAh. 

2O° 

0 

R. 

20°  4°, 

37 

15     2047 

Ah.  &  Am. 

I2o 

L. 

15°  5°, 

38 

2O     40  40 

Ah.  &  Am. 

'5 

L. 

20°   5°,  Petit.   Mai. 

Explanation :  Visual  acuity,  the  numbers  are  the  denominator  with  20  as  the 
numerator  in  all  cases.  Prisms  were  used  in  some  cases  but  failed.  Results:  In  all 
these  cases  there  was  a  decided  improvement  in  the  asthenopic  symptoms  except  in 
the  one  case  noted.  All  of  them  had  worn  glasses  some  time  with  the  most  care- 
ful correction  of  the  refraction,  but  with  no  relief.  Orthoptic  training  was  tried  but 
did  not  give  any  results.  Thirty-four  operations  for  shortening  the  externus  were  per- 
formed, and  in  a  few  a  partial  tenotomy  was  combined  with  it.  Six  cases  showed 
some  hyperphoria.  The  measurements  in  the  field  of  version  all  show  improvement. 
The  asthenopia  in  the  cases  of  Petit.  Mai.  was  improved. 


46  STRABISMUS. 

In  closing  let  me  say  I  am  trying  to  follow  nature  in 
the  movements  of  the  eye,  and,  to  quote  from  Profes- 
sor Tyndale :  "  In  dealing  with  nature  the  mind  must  be 
on  the  alert  to  seize  all  her  conditions ;  otherwise  we 
soon  learn  that  our  thoughts  are  not  in  accord  with  her 
facts." 


CHAPTER  V. 

EXOPHORIA,    OR    LATENT    DIVERGENT    SQUINT. 

THIS  condition  presents  certain  peculiarities  that  are 
not  met  with  in  its  opposite,  esophoria.  Its  correction 
when  glasses  are  used  seems  almost  impossible  ;  success- 
ful results  of  our  operations  seem  more  difficult  to  obtain, 
and  the  etiology,  primarily,  of  this  tendency  to  divergence 
seems  so  difficult  of  solution  that  any  testimony  that  will 
elucidate  this  subject  is  desirable,  while  any  theory  that 
may  include  all  cases,  not  paralytic  in  their  nature,  may  be 
acceptable  to  the  profession,  though  based  solely  on  the 
results  of  one's  own  limited  experience  in  this  field  of  oph- 
thalmology. I  may  then  state  that  if  I  express  a  sugges- 
tion or  condition  that  will  give  some  one  sufficient  data 
for  reflection  I  shall  be  more  than  repaid  for  this  effort. 
The  question  of  what  is  exophoria  is  simple  enough ;  we 
all  know  the  term  implies  a  tendency  to  divergence  of  the 
visual  lines,  or  as  some  of  my  colleagues  prefer  to  call  it, 
"insufficiency  of  convergence,"  or  "excess  of  divergence," 
but  the  nature  and  etiology  of  this  tendency  of  the  visual 
lines  to  diverge  is  to  me  a  question  of  great  importance. 
We  cannot  advance  a  suggestion  as  to  the  etiology  unless 
our  explanation  may  and  does  cover  each  and  every  case, 
primarily,  though  many  other  causes  may  be  contributing 
ones.  I  do  not  feel  satisfied  that  we  should  say  this  case 
is  due  to  an  insufficiency  of  one  function,  or  an  excess  of 
another,  nor  that  an  excess  of,  or  want  of,  innervation  of 
the  ocular  muscles  is  the  cause  of  this  divergence,  but  I 
am  more  and  more  convinced  that  it  must  be  in  the  ana- 
tomical construction  and  insertion  of  the  ocular  muscles, 
probably  congenital ;  in  other  words,  we  must  look  for  the 


48  STRABISMUS. 

cause  primarily  in  the  muscles  themselves,  and  principally 
in  that  of  the  interni.  All  the  various  theories  cannot  be 
correct,  so  the  question  arises  :  What  theory  is  the  best  ? 
And  is  the  cause  a  theory  only,  or  a  demonstrable  fact  ? 

*  "  The  conception  of  exophoria  that  seems  to  be  nearest 
to  physiological  truth  is  that  the  outward  tendency  of  the 
visual  axes  results  from  the  loss  of  convergence-impulse 
and  hence  must  be  considered  as  a  passive  rather  than  an 
active  condition."  If  this  is  a  physiological  truth  then 
there  must  be  some  fault  with  the  examination  of  the 
musculature  of  the  eye  at  the  present  time,  as  it  does  not 
agree  with  my  own  examinations  and  experience,  and  hence 
the  reason,  in  part,  for  offering  this  work  to  the  profession. 
The  movements  of  the  eyes  in  the  orbits  are  truly  wonder- 
ful physiological  phenomena,  partly  under  the  control  of 
the  will,  voluntary ;  partly  under  the  control  of  the  center 
of  convergence,  whose  limits  extend  from  the  first  position 
of  the  eyes  to  that  of  the  most  extreme  convergence,  and 
partly  beyond  the  will-power,  involuntary.  These  func- 
tional conditions  of  the  eyes  have  been  so  adjusted  by 
nature  that,  in  my  opinion,  there  is  established  a  natural 
and  a  normal  tonicity  of  the  ocular  muscles  which 
places  the  eye  in  a  position  of  rest  when  controlled  by 
the  visual  power,  and  also,  f  "  because  the  eyes  naturally 
tend  to  remain  in  this  first  position  of  the  eyes,  as  even  in 
cases  of  complete  paralysis  of  all  the  lateral  moving  mus- 
cles of  the  eyes  the  look  is  in  infinity."  This  position, 
which  we  designate  as  the  first  position  of  the  eyes,  is  one 
from  which  they  may  be  moved,  by  the  voluntary  action 
of  the  will,  to  any  secondary  position  within  the  limits 
of  the  field  of  version,  consensual  and  also  convergent  to 


*  Hansell  &  Reber.  Mus.  Anom.  of  the  Eyes,  p.  100. 
|  See  Archives,  March,  1903.     Wernicke  on  Paralysis  of   Latero- 
version. 


EXOPHORIA.  40 

the  near-point  and  by  involuntary  action,  within  the  lim- 
its of  the  field  of  fusion.  *  Maddox  evidently  seems  to 
consider  the  position  of  rest  as  that  of  the  first  position  ; 
in  other  words,  the  position  of  the  visual  lines  when  the 
look  is  in  infinity  and  slightly  below  the  horizon,  yet  he 
does  not  consider  adduction  and  abduction  as  starting 
from  this  point.  Furthermore,  it  is  an  evident  fact  that 
convergence  only  extends  or  is  controlled  from  this  posi- 
tion to  that  of  the  most  extreme  near-point,  and  if  so 
can  have  no  action,  either  active  or  passive,  to  produce 
the  condition  of  exophoria,  a  tendency  to  deviation  from 
this  first  position. 

According  to  Savage  he  would  place  f  "  the  primary 
position  of  an  eye  in  which  the  visual  axis  is  in  a  fixed 
horizontal  plane  of  the  head  and  at  the  same  time  parallel 
with  the  median  plane  of  the  head,"  but  this  position  in  the 
normal  states,  as  he  well  says,  "  can  never  be,"  except  in 
that  unnatural  condition,  "  narcosis,  or  death."  The  first 
position  of  the  eyes  must  be  found,  not  by  any  theoretical 
arguments,  but  from  the  position  as  ordained  by  nature, 
for  "  Nature  is  truth."  The  statement  that  divergence  is 
a  normal  condition  in  which  the  eyes  seek  the  position  of 
rest  cannot  be  verified  by  any  actual  experience  that  I  am 
familiar  with  ;  on  the  other  hand,  my  investigations  have 
led  me  away  from  such  conclusions,  and  that  the  position 
of  rest  is  that  of  the  first  position,  in  which  there  is  a  nor- 
mal balance  of  the  ocular  muscles,  and  that  if  otherwise 
it  is  due  to  some  anomaly  in  the  ocular  muscles  involved. 

\  Hansen  Grut  well  says,  "All  strabismus  theories,  Scher- 
ing's,  Stilling's,  Whalfor's  and  my  own,  for  instance,  are 
unsubstantial  of  course,"  but  let  us  remember  that  behind 
all  the  movements  of  the  eye  we  have  a  human  being  that 

*  Med.  Jour.,  April  i,  1893. 
f  Oph.  Myology. 
\  Prize  Essay, 


50  STRABISMUS. 

must  and  will  use  the  eyes  as  nature  intended.  If  we 
read  her  indications  aright  we  will  understand  what  is  in- 
tended as  the  perfect  standard  and  then  we  can  better 
appreciate  those  anomalies  so  often  seen  in  nature's  works, 
not  only  in  the  eye  but  in  other  parts  of  the  human  sys- 
tem. Now  Hansen  Grut  and  also  Knapp  tell  us  that  the 
position  of  rest  for  the  eyes  is  one  of  divergence,  as  to 
quote  the  former:  *  "This  position  of  rest  for  the  eyes  is 
one  of  divergence,  rarely  parallel,  and  hardly  ever  con- 
vergent," and  bases  that  opinion  on  "the  form  of  the 
orbit,  the  insertion  of  the  optic  nerve,  and  the  natural 
length  of  the  muscles  when  not  innervated,"  but  even  if 
these  anatomical  conditions  do  exist  what  have  they  to 
'do  with  the  position  of  rest  for  the  eyes  ?  Divergence  is 
said  to  be  the  natural  position  of  rest,  as  shown  when  the 
eyes  are  free  from  innervation  as  in  narcosis  or  death,  but 
as  Sweigger  well  replies,  f  "  Narcosis  and  death  are  not 
natural  conditions,"  and  in  the  living  conscious  human  be- 
ing we  have  only  to  do  with  the  functional  position  of  rest 
and  the  standard  by  which  we  compare  the  various  anoma- 
lies that  may  occur.  Baker,  writing  on  the  Anatomy  of  the 
Eyeballs,  says  :  £  "  During  sleep  or  unconsciousness  the 
eyes  turn  slightly  upwards  and  inwards,"  but  this  does  not 
agree  with  the  observations  of  others  nor  my  own  as  I  do 
not  think  that  during  sleep,  unconsciousness,  or  death,  the 
eyes  occupy  any  one  special  position,  as  they  are  deprived 
of  their  most  important  function,  the  guiding  sensation  or 
fusion  power.  I  have  given  some  attention  to  this  subject 
and  had  one  of  our  staff  at  the  New  York  Post-Graduate 
Hospital  make  some  records  for  me  as  to  the  position  of 
the  optic  axes  during  complete  anesthesia,  and  they  were 
not  found  to  be  in  any  one  direction.  I  give  the  report 
in  full,  taken  by  Dr.  H.  A.  Houghton  who  had  charge  of 
the  anesthetic  during  all  the  operations 

*  Prize  Essay,     f  Archives.     \  N.  &  O.  System. 


EXOPHORIA.  ^f 

"  Observations  in  a  series  of  forty-three  cases  in  adults, 
post-operative,  while  still  under  ether  anesthesia,  on  rela- 
tive position  of  the  optic  axes  : 

Normally  convergent  .  .11 

Slightly  divergent       ....  n 

Markedly  divergent  and  upturned     ...  6 

Right,  slightly ;  left,  normal  .             .             .  5 

Left,  slightly  divergent ;  right,  more  convergent     .  2 

Right,  divergent,  and  left  convergent           .             .  4 

Left,  divergent ;  right,  normal           ...  2 

Both  slighly  upturned  and  normally  convergent      .  2 

43" 
Further  observations  seem  to  indicate : 

(1)  All  of  the  cases  classed  as  "  markedly  divergent  and  upturned  " 
were  in  patients  of  very  low  vitality,  undergoing  severe  abdominal 
operations  and  in  a  state  of  shock. 

(2)  Babies   rarely   exhibited  any  other   than    normal    convergence 
while  under  ether.     (Not  included  in  the  above). 

(3)  Relative  positions  of  the  optic  axes  varied  much  during  opera- 
tions, and  in  many  cases  observations  would  hold  true  only  at  the 
time  they  were  made. 

(4)  It  could  hardly  be  said  that  any  single  patieint  preserved  the 
same   depth  of   anesthesia   throughout   the    whole  operation.     The 
degree  of  course  varied  with  the  work  being  done  at  the  time  by  the 
operator. 

(5)  Patients  came  to  the  table  with  various  medications   such  as 
strychnia,  morphia,  etc.,  and  also  received  the  medications  while  on 
the  table. 

(6)  Pupillary  reaction  showed  the  same  diversity  as  that  exhibited 
by  the  optic  axes. 

From  these  excellent  observations  and  my  own  clinical 
experience  I  think  that  the  visual  lines  have  no  special 
direction  when  deprived  of  their  physiological  function 
and  that,  when  the  mind  is  in  an  active  state,  the  natural 
position  of  rest  is  with  the  visual  lines  directed  forward 
toward  the  horizon  to  a  point  slightly  below  it  and  slightly 
convergent.  Primitive  man  always  uses  the  eyes  in  the 
position  of  rest  as  he  looks  in  the  distance  and,  as  is  well 


52  STRABISMUS. 

known,  his  vision  is  far  more  acute  than  that  of  those 
persons  who  live  an  urban  life,  and  pass  the  majority  of 
the  time  within  the  walls  of  their  homes. 

Hence  we  will  here  find  our  standard  position  of  rest,  our 
natural  position  of  the  visual  lines,  and  from  this  position 
we  may  understand  the  various  anomalies  of  the  eyes  as 
we  meet  them  in  the  consultation  room.  Now  in  the  study 
of  any  tendency  of  a  deviation  of  the  visual  lines  we  must 
start  from  this  natural  position  of  rest,  and  in  the  subject 
presented  we  have  a  tendency  of  the  visual  lines  to  diverge 
from  that  position.  It  goes  without  saying,  that  is  exo- 
phoria,  or  latent  divergent  squint.  Then  why  do  the  eyes 
tend  to  this  abnormal  position,  when  we  have  found  the 
standard  or  true  position  in  which  they  should  remain 
without  any  conscious  effort  or  innervation  on  our  part  ? 
Surely  not  because  the  innervation  of  the  externi  is  too 
great,  or  that  of  the  interni  less  than  normal.  Glasser 
says  :  *  "  We  cannot  have  a  continuity  of  function  without 
a  physical  organization  through  which  it  functionates,  and 
no  continuity  of  life  or  feeling  without  continuity  of  a 
regular  and  systemic  physical  organization  of  the  body 
that  binds  it  into  this  systemic  and  related  unity."  And 
again,  Reber  says :  f  "  When  some  member  has  discovered 
and  made  practical  the  use  of  a  myoplegic  that  will  para- 
lyze the  extraocular  muscles  as  a  mydriatic  does  the  intra- 
ocular muscle,  we  shall  have  made  giant  strides  toward 
solving  the  physiology  of  the  extraocular  muscles  "... 
"  It  would  probably  upset  some  of  our  pet  notions  of  to- 
day and  require  us  to  build  up  new  standards."  Perhaps 
this  paper  may  suggest  a  method  to  show  just  this  action. 

Stevens  makes  the  statement  that  exophoria  is  an 
anomaly  of  the  ocular  muscles  much  less  frequent  than 

*Med.  Rec.,  Oct.  1902. 

f  Jour.  Am.  Med.  Ass'n,  Jan.  1901. 


EXOPHORIA. 


53 


esophoria,  and  he  concedes  that  it  may  be  a  congenital 
condition  in  a  certain  proportion  of  cases,  but  why  not  in  all 
to  a  certain  extent  ?  Stevens  does  not  offer  any  very  strong 
evidence  to  the  contrary.  Landolt's  fourth  proposition 
seems  to  me  to  offer  a  suggestion  that  meets  with  my  own 
views  on  this  subject,  in  which  he  says :  *  "  Finally,  the 
fourth  form  of  insufficiency  of  convergence  is  represented 
by  cases  in  which  the  internal  recti  muscles  are  really  weak 
(or,  I  would  add,  the  externi  too  strong),  and  in  which  the 
field  of  fixation  shows  a  limitation  at  the  nasal  side.  It  is 
the  muscular  insufficiency  which  gives  rise  to  muscular 
asthenopia  when  binocular  vision  exists  but  to  divergent 
strabismus  when  it  does  not  exist."  Furthermore,  he  says  ; 
"  The  existence  of  muscular  insufficiency  has  been  denied 
as  if  the  ocular  muscles  alone  among  the  muscles  of  the 
human  body  could  neither  be  nor  become  insufficient 
for  the  work  which  they  have  to  accomplish."  .  .  . 
"  If,  instead  of  making  theoretical  systems,  trouble  were 
taken  to  thoroughly  examine  patients,  notably  their  field  of 
fixation  (version),  such  statements  would  not  be  made,"  and 
again  he  says  :  "  But  is  there  not  also  a  primary  muscular 
insufficiency,  due  to  a  congenital  defect  in  the  development 
of  one  or  even  a  group  of  ocular  muscles  ? "  Let  us,  there- 
fore, leave  out  from  our  consideration  all  cases  of  latent  or 
fixed  squint,  due  to  central  causes,  to  neurasthenia,  or  lack 
of  exercise,  and  admit  as  the  direct,  primary  cause  of  exo- 
phoria  a  defect  or  want  of  development  in  the  interni,  or 
an  excessive  development  of  the  externi  which  in  all  cases 
is  probably  congenital.  This  is  repeatedly  shown  by  the 
actual  appearance  of  the  tendons  and  muscles  during 
operations,  and  by  the  measurements  in  the  field  of  ver- 
sion, and  in  this  direction  we  shall  arrive  at  the  true 
cause  of  exophoria,  or  a  tendency  of  the  eyes  to  diverge 


N.  &  O.  System,  p.iaS,  Vol.  iv. 


54  STRABISMUS. 

either  during  the  waking  hours  or  during  sleep,  narcosis, 
or  death.  Before  proceeding  further  with  the  etiology  of 
exophoria  let  me  show  the  testimony  of  the  innervation 
theory,  that  seems  to  have  many  adherents,  but  in  which 
I  can  find  little  evidence  of  fact  beyond  the  mere  supposi- 
tion and  the  statements  of  the  writers. 

Hansen  Grut  says  :  *  "An  abnormal  innervation  which 
brings  about  muscular  contraction,  not  in  accordance  with 
binocular  vision,"  and  in  divergent  squint,  he  says  :  "  A  re- 
laxation of  convergence  innervation  to  the  position  of  ana- 
tomical rest."  Furthermore,  Hubbell  says  :  f  "A  disturb- 
ance of  oculo-motor  innervation,  accompanied  by  a  per- 
ceptible deviation  in  any  direction  of  the  visual  axis  of  one 
eye  from  the  point  of  fixation  of  the  visual  line  of  the  other 
eye."  While  Edward  Jackson  says  :  £  "  How  will  an  opera- 
tion influence  the  innervation  of  the  muscles  acting  on  the 
eyeball,  or  will  it  leave  the  innervation  quite  unaltered?" 
Jackson  does  not  answer  it,  and  it  is  one  of  the  questions 
that  I  would  like  to  have  explained,  not  asserted.  I  cannot 
find  an  answer  to  it  by  any  of  the  writers  on  the  innerva- 
tion theory,  but  we  do  know  that  an  operation  must  alter 
the  anatomical  conditions  of  the  muscles,  increasing  their 
functions,  if  we  shorten  the  muscular  length,  and  decreas- 
ing their  functions  if  we  set  the  insertion  of  the  tendon 
farther  back  on  the  eyeball  by  a  tenotomy ;  if  so,  it  must 
be  very  obvious  that  the  same  degree  of  innervation  will 
have  an  increased  or  a  decreased  action,  respectively,  on 
the  movements  of  the  eyeball  in  the  field  of  fusion  and 
in  that  of  fixation.  Furthermore,  can  this  innervation 
theory  be  proved  by  any  actual  experience  ?  If  we  study 
the  movements  of  the  eyeballs  in  the  field  of  version,  the 


*  Prize  Essay. 

f  N.  Y.  State  Jour,  of  Med,,  Nov.  1901. 

J  Med.  News,  Nov.  1902. 


EXOPHORIA. 


55 


extent  of  that  field  must  be  limited  by  the  actual  power  of 
the  muscle  to  turn  the  visual  line,  during  contraction,  to 
the  greatest  extent  of  the  field.  Here  is  all  the  inner- 

o 

vation  and  all  the  muscular  power.  Does  an  operation 
change  the  innervation  or  the  anatomical  conditions  ? 

o 

The  answer  seems  obvious.  In  many  cases  the  turning  of 
the  visual  line  is  far  below  the  normal,  though  there  is 
no  diplopia,  and  the  patient  may  exert  his  greatest  will 
power.  This  seems  to  me  due  more  to  the  anatomical 
construction  of  the  muscles  and  to  their  insertion  than  to 
the  degree  of  innervation. 

In  the  movements  of  the  eyeballs  in  the  field  of 
version  there  is  little  or  no  resistance,  except  that  of  the 
antagonistic  eye  muscles,  which  we  know  are  relaxed  to 
meet  all  the  requirements  of  the  contracting  muscles, 
hence,  innervation  can  and  does  influence  the  movements 
of  the  eye  as  the  needs  of  vision  require  and  the  actual 
power  of  the  muscles  will  allow  to  the  extent  of  the 
field  of  version.  When  we  consider  the  statement  that 
exophoria  is  due  or  caused  by  myopia  and  the  position 
of  rest  as  suggested  by  Bonders'  "Antithesis,"  and  in 
Hansen  Grut's  essay  on  strabismus  we  find  some  reason 
for  these  statements  if  we  look  at  the  question  from  the 
myopic  standpoint ;  that  is  to  say,  if  we  consider  the 
cases  of  myopia  first,  and  then  the  imbalance  of  the 
ocular  muscles.  In  this  way  we  will  notice  that  most 
of  the  cases  of  myopia  do  have  a  tendency  to  exophoria, 
but  on  the  other  hand,  or  conversely,  if  we  study  our 
cases  from  the  exophoric  standpoint,  that  is,  to  note 
the  exophoria  first,  in  all  cases  of  asthenopia,  either 
refractive  or  muscular,  we  find  that  the  large  majority  of 
them  are  not  myopic,  but  that  hyperopia  and  hyperopic 
astigmatism  predominate  in  about  the  same  degree  as  in 
all  other  conditions  of  refraction  or  muscular  imbalance. 
I  have  the  records,  more  or  less  complete,  of  sixty-eight 


56  STRABISMUS. 

cases  of  exophoria  and  thirty-seven  cases  of  exotropia,  a 
total  of  one  hundred  and  five  cases.     These  examinations 
were  nearly  all  made  in  my  office  and  are  fairly  correct  in 
all  the  objective  and  subjective  tests.     Of   this  series  of 
cases    that    showed    exophoria   we    have    fifty    cases    of 
hyperopia  and  of  hyperopic  astigmatism  ;  fourteen  cases 
of  myopia  and  myopic  astigmatism  and  four  with  emmet- 
ropic  refraction,  and  in  the  cases  of  exotropia  or  actual 
turning  of  the  visual  lines  outward,  we  find  twenty-four 
cases  of  hyperopia  and  hyperopic  astigmatism ;  seven  of 
myopia  and  myopic  astigmatism  ;  one  noted  as  emmet- 
ropic,  and  four  in  which  the  refraction    was    not   noted  ; 
these  latter  were  clinical  cases.     If  these  records  are  cor- 
rect, and   I  think  I  can  vouch  for  all  the  office  examina- 
tions, then  myopia  and  the  position  of  rest  cannot  be  the 
original  cause  of  actual  divergence  or  a  tendency  to  di- 
vergence of  the  visual  lines.     Is  it  not  reasonable,  from  a 
history  of  these  cases,  to  believe  we  must  look  for  some 
other  cause  for  this  tendency  of  the  visual  lines  than  the 
old  classical    ones  ?     All    these  cases,  by  a  most  careful 
and  repeated  examination  did   show   a  tendency  of   the 
visual  lines  to  deviate  outward  while  the  refraction  was 
as  carefully   estimated    by    the   objective   and    subjective 
tests,  yet  the  cases  of  myopia  were  very  small  in  number 
as  compared  with  the  total. 

If  this  argument  has  any  force  whatever  then  that  of 
the  "  relaxation  of  convergence  innervation,"  etc.,  cannot 
be  much  in  evidence.  We  have  tried  to  prove  that  the 
position  of  rest  must  be  assumed  to  be  that  of  the  first 
position  of  the  eyes,  in  which  the  ocular  muscles  are  in  a 
state  of  normal  equilibrium  produced  by  the  normal 
anatomical  size,  insertion  and  tonicity  of  these  muscles. 
Then,  if  there  is  an  anomaly  of  this  natural  condition, 
the  eyes  will  tend  to  that  position  brought  about  by  the 
abnormal  condition  of  the  ocular  muscles.  That  is  to 


EXOPHORIA. 


57 


say,  if  the  anatomical  conditions  of  the  abductors  or 
externi  will  exert  greater  power  on  the  lateral  rotation  of 
the  eyeball  than  that  of  the  adductors  or  interni  then  the 
position  of  rest  will  be  one  of  divergence  and  only  in 
that  way.  Hence  myopia  cannot  be  the  determining 
cause  of  exophoria.  Swan  Burnett  says  of  convergent 
squint,  "this  condition  is  the  legitimate  result  of  the 
greater  power  and  activity  of  those  (interni)  muscles,"  a 
remark  that  must  also  apply  with  equal  force  to  that  of 


TROPOMETER  OF  STEVENS. 


the  externi  in  exophoria.  To  continue  our  argument  as 
to  what  is  the  etiology  of  exophoria,  a  still  further 
confirmation  of  my  views  may  be  found  in  the  field  of 
version.  In  other  articles  on  the  subject  of  heterophoria 
of  the  convergent  class  I  have  considered  the  theories  of 
other  writers  and  have  advanced  as  my  own  that  I 
believed  it  was  primarily  due  to  the  muscular  condition 
of  the  eyes,  in  other  words,  the  power  of  the  straight 
muscles  to  move  the  eyes  in  the  field  of  version  and  in 


58  STRABISMUS. 

the  field  of  fusion.  This  has  been  called  the  Anatomical 
or  Muscular  theory  and  in  my  opinion  is  the  true  cause 
of  all  cases  of  heterophoria  or  heterotropia.  I  have  been 
still  further  convinced  of  this  muscular  theory  as  the  true 
cause  of  latent  or  fixed  squint  from  the  use  of  one  of  the 
most  reliable  instruments  in  the  objective  study  of  heter- 
ophoria. I  refer  to  the  tropometer  devised  by  Stevens. 
This  instrument  measures  the  rotation  of  the  eyeball 
about  its  common  center  in  the  horizontal  and  vertical  axes 
by  a  practical  and  useful  method,  cito,  tuto,  et  jucunde. 
It  is  far  more  exact  than  other  methods  for  the  measur- 
ments  of  the  field  of  version,  as  that  of  the  perimeter,  the 
strabisometer,  or  that  of  noting  the  movements  of  the  eye 
as  it  follows  a  pencil,  etc.  In  my  opinion,  it  is  to  hetero- 
phoria what  atropine  is  to  the  correct  examination  of 
refraction.  I  do  not  think  innervation  can  have  any- 
thing to  do  with  the  movements  of  the  eyeballs  in  the 
field  of  version  except  as  they  pass  from  point  to  point 
under  the  influence  of  the  will.  Does  not  innervation 
stimulate  the  muscles  to  action  and  do  not  the  muscles 
act  just  so  far  as  their  individual  power  will  permit,  or, 
more  clearly,  just  as  far  as  the  muscle  fibres  will  or  can 
contract  ?  On  contraction  of  these  muscle  fibres  the  eye- 
ball may  be  moved  a  certain  distance  in  one  individual 
and  more  or  less  in  another ;  one  may  do  a  certain  piece 
of  work  with  ease,  another  cannot  accomplish  as  much, 
yet  each  may  exert  the  same  nerve  force  or  the  same 
muscle  innervation,  but  one  has  a  greater  development  of 
the  muscular  system,  the  other  less.  Similarly  is  it  not 
so  with  the  muscles  which  move  the  eyeballs  ?  Nature's 
effort  is  to  build  us  all  in  the  same  way.  She  has  her 
rules  that  in  the  vast  majority  of  individuals  are  carried 
out  successfully  and  one  muscle  is  always  made  stronger 
than  another  one,  according  to  our  physical  needs,  but 
contrariwise,  in  some  individuals,  nature  seems  to  have 


EXOPHORIA. 


59 


worked  at  cross  purposes  and  we  find  a  deficiency  of 
power  in  muscles  that  should  be  stronger,  to  attain  the 
natural  uses  of  the  system. 

To  illustrate,  we  know  that  in  the  normal  field  of  ver- 
sion, as  repeated  in  our  text-books  and  shown  in  our  clin- 
ical work,  that  the  contraction  of  the  interni  is  greater 
than  that  of  the  externi,  as  fifty-five  is  to  fifty.  Further- 
more, in  the  field  of  fusion,  the  power  or  dynamics  of  the 
interni  is  greater  than  the  power  of  the  externi,  generally 
as  three  is  to  one.  (This  proportion  is  generally  con- 
ceded). Such  is  the  way  nature  built  and  intended  that 
the  lateral  balance  of  the  ocular  muscles  should  act,  a 
fact  that  is  well  proved  in  the  needs  of  our  daily  life.  In 
exophoria  the  natural  process  is  reversed  and  we  find 
the  power  of  the  externi  much  greater,  more  or  less,  than 
what  it  should  be  normally.  Hence,  undoubtedly  we  must 

have  the  tendency 
of  the  eyes  or  the 
visual  line  to  devi- 
ate outward.  Now 
to  resume,  if  we 
would  measure  the 
action  of  the  lat- 
eral muscles,  the 
findings  of  the 
tropometer  being 
objective,  it  must 
indicate  if  the  mus- 
cles are  acting 
normally  or  if  we 
have  present  an 
anomaly  in  their  action.  Then  what  is  the  normal  action 
of  the  lateral  muscles  of  the  eyes  as  shown  by  the  tro- 
pometer? Vertically,  we  find  about  eighty  degrees  of 
rotation,  starting  from  the  first  position  of  the  visual 


SCALE  FOR  THE  TROPOMETER.      DOTTED  LINE  SHOWS 
POSITION  OF  EDGE  OF  CORNEA  IN   ROTATION. 


6o  STRABISMUS. 

lines,  about  thirty  degrees  upward  and  fifty  degrees 
downward.  Similarly,  measuring  the  lateral  movements 
and  starting  from  the  same  position,  we  have  about 
fifty-five  degrees  inward  and  fifty  degrees  outward. 
This  is,  in  my  experience,  about  the  normal  move- 
ment of  the  visual  lines  from  that  of  the  position  of  rest 
to  the  extreme  limit  of  the  field  of  version,  in  other  words, 
the  excursions  of  the  cornea  about  the  center  of  rotation 
when  the  eyes  are  normally  balanced.  Stevens,  I  believe, 
gives  the  conditions  essential  for  this  examination  to  be 
the  immobility  of  the  head ;  the  adjustment  of  the  in- 
strument ;  the  exact  focus  and  the  effort  of  the  examiner 
to  bring  out  the  complete  movements  of  the  eyes  in  the 
field  of  version.  Accepting  the  above  measurements  as 
that  of  the  standard  movements  in  this  field  then  what 
will  the  tropometer  show  in  a  case  of  exophoria  ?  I  will 
illustrate  by  one  of  my  cases  : 

No.  3274. — R.  E.,  up  30°,  down  60°,  in  40°,  out  50°. 
L.  E.,  up  30°,  down  60°,  in  50°,  out  60°. 

I  think  this  will  speak  for  itself  as  to  the  tendency  of  the 
eyes  to  turn  outward,  while  that  of  the  lower  field  seems 
to  be  a  little  more  than  the  normal.  In  the  field  of  fusion 
the  eyes  should  turn  inward  two  or  three  times  greater 
than  the  outward  movement  and  a  little  more  downward 
than  upward,  the  upward  rotation  being  very  slight  if 
normal.  As  if  adduction  shows  an  in-turning,  at  the  first 
examination,  under  the  stimulation  for  fusion,  of  twenty 
degrees  and  eight  degrees  out-turning  we  will  have  a 
normal  balance  in  that  field,  while  any  decided  difference 
in  this  proportion  will  probably  indicate  an  anomaly  in 
the  balance  of  the  ocular  muscles.  I  would  illustrate  this 
with  case  No.  3206,  in  which,  after  repeated  trials,  the 
abduction  was  15°,  and  the  adduction  also  15°,  and  this 
disproportion  between  the  normal  and  that  of  the  exces- 
sive power  of  the  externi  is  particularly  obvious  and  shows 


EXOPHORIA.  6 1 

an  exophoria  or  tendency  to  turn  outward  of  the  visual 
lines  and,  as  the  examinations  in  this  case  were  repeat- 
edly made  with  the  same  final  result,  the  indications  for 
its  correction  are  easily  understood. 

The  symptoms  of  exophoria  may  occur  at  any  age. 
The  time  at  which  they  complain  is  not  fixed,  that  is  to 
say,  at  no  special  time  of  life  are  the  symptoms  of  ocular 
muscle  strain  developed.  According  to  my  records  the 
youngest  is  fifteen  years  old,  and  from  that  up  to  fifty-five 
they  have  presented  the  evidences,  both  objective  and 
subjective,  of  a  want  of  muscular  balance,  as  shown  by  the 
tropometer  and  the  test  with  prisms.  Their  subjective 
symptoms  are  usually  some  of  the  following  :  Pain  in  the 
eyes,  frontal  headache,  pain  extending  from  the  eyes  over 
the  head  or  back  of  the  neck  and  down  the  spine,  inability 
to  read,  nausea  and  vomiting,  particularly  when  riding  in 
the  cars,  localized  pain  in  the  head,  lacrymation,  eyes  feel 
tired  and  strained,  vision  blurred  and  conjunctival  irrita- 
tion. Many  of  these  symptoms  are  relieved  by  the  use  of 
glasses.  The  patients  feel  much  better  but  still  cannot  con- 
tinue their  daily  work  with  comfort  and  ease.  All  of  my 
patients  had  been  wearing  glasses  to  full  correction  before 
they  came  to  me  and  if  their  glasses  were  not  correct  in 
my  estimation  I  invariably  gave  them  a  careful  examina- 
tion and  full  correction  and  these  glasses  were  worn  a  rea- 
sonable time  before  any  other  procedure  was  attempted. 
As  to  the  use  of  prisms,  combined  with  the  glasses,  they 
have  seemed  useful  in  some  cases,  but  I  have  little  con- 
fidence in  the  use  of  prisms  for  constant  wear  and  think 
it  is  much  better  to  operate  in  all  these  cases.  If  they 
refuse  to  submit  to  an  operation  then  the  wearing  of 
prisms  may  be  useful  for  a  time  but  my  experience  has 
not  been  particularly  happy  with  their  use  in  my  office 
work.  Very  many  of  these  cases  of  exophoria  pre- 
sent the  condition  known  as  insufficiency  of  the  interni 


62  STRABISMUS. 

that  is  to  say  the  power  of  the  interni  to  rotate  the 
eyes  inward  and  to  cause  the  visual  lines  to  converge 
seems  to  be  much  weaker  than  normal,  while  the  power  of 
the  externi  to  produce  divergence  is  about  the  same  as 
normal.  In  these  cases  I  have  found  some  benefit  in  a 
careful  systematic  exercise  of  the  interni,  but  I  consider 
all  these  suggestions,  as  the  wearing  of  prisms  or  that  of 
exercise  of  the  interni,  as  simply  putting  off  a  procedure 
that  should  be  done,  as  all  these  artificial  aids  eventually 
fail  to  have  their  beneficial  effect.  Of  all  my  series  of 
cases  as  reported,  every  one  showed  well  marked  evidence 
of  exophoria  after  repeated  trials  of  the  muscular  balance 
and  all  of  them  submitted  to  the  necessary  operations.  In 
no  case  was  this  done  more  than  four  times  and  in  the 
large  majority  only  one  or  two  operations  were  performed. 
The  refraction  of  all  these  cases  presented  the  usual  pro- 
portion, as  found  in  office  work  at  the  present  time. 
The  largest  number  being  hyperopicwith  astigmatism  and 
a  very  small  number  with  myopic  astigmatism,  only  one- 
fifth  of  the  entire  number.  Of  the  operations  performed 
sixty-eight  were  tenotomies  of  the  externi,  and  eighteen, 
shortening  of  the  internal  rectus. 

Diagnosis.  The  diagnosis  of  this  condition  of  imbalance 
of  the  ocular  muscles  should  not  be  very  difficult  if  we 
accept  one  cause  which  underlies  all  others  and  some  cer- 
tain standard  measurements  that  will  represent  the  nor- 
mal movements  of  the  eyeballs  in  the  fields  of  version  and 
that  of  fusion.  Deviations  from  these  standards  must 
be  taken  into  consideration,  most  careful  examinations 
made,  and,  unless  postively  indicated,  all  other  means 
of  relief  should  be  considered  before  any  operation  is  per- 
formed. The  field  of  version  or  fixation  has  been  well 
demonstrated  in  our  recent  text-books.  Landolt  speaks 
fully  on  these  important  excursions  of  the  eyeballs  taken 
from  the  arc  of  the  perimeter  and  using  the  finest  type  or 


EXOPHORIA. 


two  small  dots  as  the  test.  •  One  of  these  should  be  carried 
along  the  arc  of  the  perimeter,  placed  horizontally  to  the 
most  extreme  point  of  clear  vision,  that  is  to  say,  with  the 
head  fixed  and  the  eyes  turned  inward  or  outward  as  far 
as  possible  to  the 
point  where  the 
finest  type  or  the 
two  dots  can  b  e 
distinctly  seen. 
The  degrees  shown 
on  the  arc  of  the 
perimeter  are  the 
angular  deviation 
from  the  first  posi- 
tion, to  the  posi- 
tion of  the  visual 
lines  in  the  extreme 
fi  e  1  d  of  fixation. 
Landolt's  chart  of 
the  normal  fi  e  1  d 
shows  these  limits 
of  rotation  of  the 
eyeballs,  though  his  measurements  are  somewhat  smaller 
than  my  own  or  those  shown  by  the  tropometer.  In  the 
measurements  of  the  power  of  each  individual  muscle 
to  rotate  the  eyeball  about  the  center  of  rotation 
the  tropometer  gives  very  accurate  information. 
We  do  not  depend  upon  what  the  patient  sees,  we 
simply  note  the  excursions  of  the  cornea  in  any  direc- 
tion, and  measure  the  movements  of  its  edge  on  the 
scale  of  the  instrument.  In  considering  the  results  of 
these  examinations,  Stevens,  at  one  time  advanced  the 
proposition  that  the  upward  movements  were  the  most 
important  and  the  possible  clue  to  all  the  conditions  of 
heterophoria.  I  regret  that  at  the  present  time  he  seems  to 


SKEEL'S  PERIMETER. 


64  STRABISMUS. 

have  abandoned  that  proposition  and  now  considers  the 
torsion  of  the  eyeball  and  its  anomalies  as  the  determin- 
ing cause,  yet  he  has  not  fully  decided  just  where  and 
when  we  shall  find  the  true  cause  of  all  our  cases  of 
heterophoria  and  heterotropia.  Be  all  that  as  it  may,  I 
still  feel  that  while  innervation  may  stimulate  the 
muscles  to  act  and  that  other  causes  may  contribute  to 
this  tendency  of  the  visual  lines  to  diverge,  yet  all  these 
conditions  must  be  controlled  by  the  physical  power  of 
each  individual  muscle  to  contract  under  the  nerve 
stimulation  and  that  all  these  cases  of  exophoria  have  a 
want  of  muscular  power  in  the  interni,  which  is  readily 
and  objectively  shown  by  the  measurements  of  the  tro- 
pometer. Hence,  if  we  accept  a  standard  inward  and 
outward  lateral  rotation  of  the  eye  and  that  the  tropom- 
eter  shows  the  outward  rotation  greater,  or  the  inward 
rotation  less,  than  normal  we  must  have  the  condition 
known  as  exophoria.  I  accept  then  a  normal  field  of 
version  and  any  decided  deviation  from  this  must  be 
due  to  some  want  of  physical  power  in  the  muscles 
themselves.  We  may  have  cases  which  show  a  restricted 
movement  in  all  directions  with  about  the  same  relative 
degree  in  each.  These  I  consider  simply  cases  of  a 
general  anaemic  condition  and  not  those  of  heterophoria, 
but  when  we  get  a  decided  overaction  or  weakness  of  any 
one  or  more  muscles  as  shown  by  the  tropometer  then  I 
think  we  have  some  positive  signs  of  heterophoria.  To 
illustrate  this  in  connection  with  our  paper  the  tropometer 
will  show  : 

CASE  No.  3206. —  Exophoria.  Adduction=  15°  ;  Abduction  =  15 ° . 
Tropometer,  up,  25°;  down,  55°;  inward,  45°;  outward,  50°.  Or 
CASE  No.  3274. —  Slight  Divergent  Squint.  Tropometer  shows,  in- 
ward, 40°;  outward,  50°. 

Here  we  clearly  see  the  difference  between  the  rotary 
power  of  the  lateral  moving  muscles,  in  which  the  excur- 
sions of  the  eyeballs  are  just  reversed  from  that  of  the 


EXOPHORIA.  65 

normal  relations  ;  in  simple  words,  greater  power  to  turn 
out  than  to  turn  in.  An  instrument  so  useful  and  objec- 
tive in  its  findings  should  be  always  used  before  any 
attempt  is  made  to  correct  an  heterophoria  of  any  degree. 


CASE  OF  SQUARE  PRISMS. 

Next  in  importance  is  that  of  the  prism  test,  one  that  is 
mostly  objective  and  very  reliable.  I  have  advocated  the 
use  of  this  test  for  many  years  and  still  feel  the  fullest 
confidence  in  its  findings  when  properly  used,  though 
many  of  my  colleagues  have  tried  to  convince  me  that 
we  cannot  test  the  power  of  an  individual  muscle  in  this 
way  and  that  the  power  of  one  is  only  an  indication 
of  the  power  of  some  other  muscle  holding  the  eye  in 
the  first  position,  but  the  strongest  and  most  impor- 
tant function  of  the  eye  and  the  keynote  of  binocular 
vision  is  that  of  the  fusion  power  or  guiding  sensation. 
This  function  is  not  stimulated  unless  the  rays  fall  upon 
some  other  part  of  the  retina  outside  of  the  macula  region. 
The  use  of  this  test  by  repeated  examinations  and  its 
results  confirmed  by  other  tests  will  make  the  diagnosis 
of  exophoria  clear  and  at  the  same  time  indicate  the 
most  suitable  procedure. 

In  the  diagnosis  of  exophoria  or  any  condition  of  het- 
erophoria, I  cannot  place  any  reliance  on  the  tests  for  a 
deficiency  of  power  or  overaction  of  the  ocular  muscles  that 


66  STRABISMUS. 

will  deprive  the  eyes  of  their  visual  power  in  any  way. 
That  is  to  say,  we  must  not  lower  the  visual  acuity,  by 
reduced  illumination,  blurring  of  the  vision,  deviation  of 
the  rays  to  the  periphery  of  the  retina,  parallax  test,  cover 
test,  etc.,  if  we  would  know  the  full  and  true  muscular 
power  of  the  eyes  in  the  field  of  fusion  ;  nevertheless, 
all  of  these  various  procedures  are  useful  as  confirmatory 
tests  for  any  muscular  imbalance  shown  by  what  I  con- 
sider much  more  practical  and  standard  tests.  We  must 
consider  all  the  various  conditions  that  control  the  move- 
ments of  the  eyeballs,  apart  from  their  special  function. 
The  nervous  supply  controlling  the  movements  of  the 
eye  consists  of  no  less  than  four  of  the  cranial  nerves,  one- 
"third  of  the  entire  number,  with  that  of  the  special  func- 
tion, convergence,  controlled  by  a  special  center,  lying  in 
the  mid-line  of  the  brain  and  in  the  region  of  the  Aqueduct 
of  Sylvius  and  the  fourth  ventricle.  This  special  nucleus 
while  it  seems  to  control  the  action  of  convergence,  does 
not  produce  nor  cause  exophoria  when  paralyzed.  Fur- 
thermore, may  we  not  consider  the  actions  of  the  eyeballs 
as  those  of  control,  directed  by  the  higher  centers  of  the 
brain,  the  hemispheres,  as  shown  in  the  field  of  version 
and  those  which  are  automatic,  directed  by  the  lower  brain 
centers,  as  the  Medulla  and  the  Pyramidal  Tracts.  These 
lower  centers  seem  to  control  the  act  of  fusion  and  that 
of  convergence.  Hence  I  cannot  favor  any  test  that  will 
disturb  these  important  functions.  Now  there  is  a  stand- 
ard of  all  these  functions  of  the  eye.  It  is  invariably 
found  in  the  normal  eye  and  must  exist  in  the  vast  major- 
ity of  all  human  beings.  It  is  the  typical  eye  of  nature 
and  under  all  reasonable  conditions  this  eye  will  never 
suffer  from  muscular  asthenopia.  Before  proceeding  with 
the  method  of  using  the  prism  test  I  wish  to  state  that  the 
power  of  abduction  as  shown  by  this  test  is  not  always  the 
key  to  a  solution  of  our  problem  nor  is  it  a  fixed  condition, 


EXOPHORIA. 


as  under  certain  procedures  I  have  found  the  power  of 
abduction  to  vary  very  much  from  the  first  tests.  In  the 
use  of  the  prism  test  with  the  base  in,  testing  the  power 
of  the  externi  to  rotate  the  visual  line  outward  under  the 
guiding  sensation,  the  patient  should  be  able  to  fuse  or 
blend  the  images  of  a  candle,  placed  at  twenty  feet  with  a 
prism  of  eight  degrees  or  centrads.  This  is  about  the 
normal  power  of  the  externus,  though  it  may  vary  from 
this  and  yet  be  in  perfect  balance  according  to  the  power 
of  adduction.  If  the  eight  degree  prism  can  be  overcome 
by  the  eye  turning  outward  then  we  increase  the  angle  of 
the  prism  and  if  it  rises  as  high  as  ten,  twelve  or  more 
degrees  we  have  probably  an  exophoria.  Now  repeatedly 
test  the  power  of  adduction  (the  normal  power  of  adduc- 
tion is  about  twenty-four  degrees  at  the  first  or  second 
examination)  and  if,  after  these  repeated  trials  we  can  only 
get  fusion  of  the  images  with  a  prism  of  less  deviating 


MADDOX   COMPOUND    ROD.  MADDOX    SIMPLE    ROD. 

power  than  that  of  the  externi  the  evidence  of  exophoria 
is  almost  complete,  particularly  if  the  field  of  fixation  or 
version  shows  the  same  outward  tendency  of  the  visual 
lines.  I  place  almost  complete  reliance  on  the  findings  of 
these  two  tests,  at  the  same  time  I  use  as  confimatory 
tests  first  the  power  of  convergence  as  shown  by  the  fu- 
sion near-point,  the  cover  test,  to  note  the  rotation  of  the 
eye  when  deprived  of  the  visual  power,  and  the  Maddox 
rod  test  or  the  old  vertical  diplopia  test  to  note  the  devi- 


68  STRABISMUS. 

ation  of    the  eyes  when  deprived  of    the  fusion    power. 
These  last  tests  are  very  useful  in  prescribing  prisms. 

Treatment.  In  my  experience  the  correction  of  exopho- 
ria  is  one  of  the  most  difficult  problems  in  ophthalmic  pro- 
cedures,—  the  fusion  force  of  the  eye  is  so  low  in  the  field 
towards  the  nose  ;  the  power  of  the  externi  to  turn  the  eye 
outward  in  the  field  of  fusion  is  very  small ;  the  muscle 
itself  when  operated  upon  is  generally  found  more  or  less 
relaxed,  nor  does  it  respond  to  orthoptic  training  as  read- 
ily as  the  interni,  if  at  all,  and  the  use  of  glasses  seems  to 
have  very  little  effect  on  the  tendency  of  the  eyes  to  turn 
outward.  But  in  all  cases  of  evident  exophoria  as  shown 
by  the  tests  for  that  condition,  if  they  have  not  been  sup- 
plied with  the  correct  and  suitable  glasses,  I  would  first 
fully  correct  any  refractive  error  that  may  exist,  under  a 
mydriatic,  if  necessary.  Let  these  glasses  be  worn  con- 
stantly for  some  time,  though  I  do  not  believe  that  any 
refractive  error  is  the  cause  of  the  exophoria,  yet  the  full 
correction  of  a  myopia,  from  the  more  distinct  retinal 
images  formed,  must  increase  the  fusion  power  of  the  eye 
and  in  this  way  we  may  have  an  increase  in  the  power  of 
adduction.  I  think  this  will  only  apply  to  cases  of  myopia, 
while,  on  the  other  hand,  in  exophoria  associated  with 
other  refractive  conditions  glasses  will  be  of  very  slight 
service. 

The  use  of  tonics,  as  Strychnia,  etc.,  and  out-of-door 
exercise  may  be  indicated  in  some  cases,  particularly 
when  following  any  severe  illness,  yet  even  these  cases 
may  show  fairly  good  adduction  and  convergence  and 
the  improvement  will  only  be  in  the  general  condition. 
Our  next  step  in  the  line  of  treatment  may  be  that  of 
orthoptic  training,  by  prism  exercise,  for  the  interni,  two 
or  three  times  a  week.  As  to  the  method  with  which 
this  exercise  shall  be  used  there  seem  to  be  as  many 
suggestions  as  there  are  writers  on  the  subject.  In  my 


EXOPHOR1A.  69 

experience  the  stimulation  of  the  interni  by  the  use  of  a 
weak  prism  placed  over  first  the  one' eye  then  the  other, 
with  the  base  outward  every  few  seconds  as  the  images 
unite,  for  five  minutes,  has  been  serviceable,  but,  as 
Winters  well  says,  "  Muscular  power  developed  in  this 
way  is  not  permanent,"  as  when  the  exercise  is  stopped 
the  original  condition  soon  returns  and  the  symptoms 
reappear.  Before  proceeding  to  the  consideration  of  an 
operation  there  yet  remains  the  method  of  prescribing 
prisms  for  constant  use  placed  with  the  base  of  the  prism 
over  the  internus.  I  do  not  fully  approve  of  this  proced- 
ure, yet  in  some  cases,  where  we  meet  with  a  decided  ob- 
jection to  any  operative  interference,  they  may  be  tried. 
For  this  purpose,  after  the  degree  of  the  outward  ten- 
dency has  been  carefully  estimated  with  Maddox's  rod 
or  the  vertical  diplopia  test,  we  may  order  prisms  of  equal 
degree  for  each  eye.  There  seems  to  be  some  limit  to 
this,  as  few  patients  will  tolerate  more  than  a  correction 
of  six  degrees  of  exophoria  with  a  prism  of  two  or  three 
degrees  over  each  eye.  Still  the  use  of  prisms  is  only  a 
temporary  condition ;  as  the  effect  is  not  permanent,  they 
tend  to  develop  and  to  increase  the.  tendency  to  devia- 
tion and  simply  postpone  the  time  when  we  must  come  to 
the  final  and  permanent  result  of  an  operation.  All  these 
methods  should  be  odven  a  reasonable  and  serious  trial 

o 

before  we  approach  the  proposition  of  an  operation. 
Failing  then  in  all  our  procedures  to  correct  the  symptoms 
or  to  produce  a  constant  and  fixed  result,  we  not  only 
must  decide  on  an  operation,  but  also  the  very  important 
question,  What  operation  to  perform  ?  Here,  in  my 
experience,  comes  a  very  serious  question,  as  we  must 
decide  whether  our  case  of  exophoria  is  due  to  a  weak- 
ness of  the  interni,  deficient  adduction,  or  increase  in  the 
power  of  the  externi,  increased  abduction.  If  we  have 
the  latter  condition,  that  is  to  say  if  we  find  the  abduction 


STRABISMUS. 


very  high,  of  ten  or  more  degrees  of  prism  deviation,  then 
we  may  consider  the  power  of  the  externi  as  too  great 
and   a  tenotomy,    partial    or  complete,   on   one   or    both 
externi,  will  be  the  first  steps  in  our  operative  procedure, 
to  be  followed,   if  necessary,  by  a  strengthening  of  the 
interni.       Conversely,    if    we    find    the    abduction    eight 
degrees   or  less,   with   the  same   tendency  to  exophoria, 
then  any  procedure  that  will  tend  to  weaken  the  power 
of  the  externi  is  not  indicated,  but  we  must  increase  the 
power  of  the  interni  by  a  suitable  operation.      For  this 
purpose    I    think    the    operation    for   shortening   of    the 
interni,   one    or  both,   is  the  best  and  safest  procedure. 
This  operation  of  a  "tuck"  in  the  interni  was  originally 
performed  by  me  with  the  catgut  suture  and  has  seemed 
to  me  to  be  the  best,  most  rational  and  most  certain  in  its 
effects  on  the  muscular  balance.     This  operation  is  well 
known,  having    been    many   times  described    by    others, 
with  the  use  of  the  silk  suture,  which  requires  another 
operation  to  remove  it,  and  by  myself  with  the  use  of  the 
catgut  suture  where  the  advantages  are   obvious.     This 
procedure  is  simple  in  its  technique,  easy  of  performance 
and  very  gratifying  in  its  results,  while  being  perfectly 
free    from    any    danger   of    overcorrection.       As   to    the 
advisability    of   an    advancement    of   the  tendon    of   the 
interni  in  these  cases  it  has  seemed  to  me  too  much  of  a 
formidable  operation  and  is  not  needed  nor  indicated  in 
these  conditions  of  imbalance.     Stevens  says:     "Every 
modification  of  the  length  of  a  lateral  muscle,  by  relax- 
ation or  by  shortening,  which  can  in  any  degree  effect  the 
rotation  of  an  eye,  must  in  every  instance  be  accompanied 
by  an  exactly  equivalent  modification  of  the  correspond- 
ing muscle  of  the  other  eye. "     This  rule  does  not  meet 
my  full  approval  as  while  it  may  and  probably  does  hold 
good  is  most  cases  of  exophoria  that  require  an  operation, 
as  the  increased  effect  is  generally  needed,  yet  it  seems  to 


EXOPHORIA.  >ji 

me  and  has  been  so  in  my  past  experience,  that  the 
extent  of  all  our  operative  procedures  must  depend  on 
the  extent,  or  degree  of  the  tendency  to  a  deviation. 
That  is  to  say,  if  the  evidence  of  an  exophoria  is  very 
slight  and  yet  needs  an  operation  for  its  correction,  we 
may  very  reasonably  reduce  the  power  of  an  externus  or 
increase  the  power  of  an  internus  and  then  note  the  effect 
on  the  field  of  fusion  and  on  that  of  fixation.  If  this 
simple  procedure  has  been  sufficient  surely  no  further 
operative  interference  will  be  needed.  I  have  the  records 
of  many  cases  where  only  one  operation  has  been  per- 
formed and  an  examination  after  several  years  has  shown 
that  the  result  had  been  permanent.  The  effect  of  an 
operation  on  one  lateral  moving  muscle  is  almost  invari- 
ably shown  in  the  power  of  the  corresponding  muscle 
of  the  other  eye  or  has  been  so  in  my  experience  as 
shown  by  many  records  and  I  have  considered  this  due 
to  the  physiological  action  of  binocular  adjustment  of  the 
visual  lines.  This  is  well  demonstrated  in  the  permanent 
correction  of  convergent  squint  by  a  simple  tenotorny  of 
one  internus. 

Conclusions  :  That  exophoria  is  frequently  met  with 
in  ophthalmic  practice  in  the  investigation  of  the  refrac- 
tive condition,  as  shown  by  the  examination  with  the 
tropometer,  the  prisms  and  the  cover-test. 

That  the  primal  cause  of  exophoria  is  an  antecedent 
weakness  of  the  interni  and,  in  some  cases,  an  increase  in 
the  power  of  the  externi,  both  conditions  being  probably 
congenital. 

That  it  is  very  difficult  to  bring  about  a  perfect  adjust- 
ment of  this  imbalance  of  the  ocular  muscles,  but  that  a 
careful  adjustment  of  this  imbalance  will  give  constant  and 
decided  relief,  and  in  the  majority  of  cases  an  operation 
is  to  be  preferred  to  all  other  procedures  as  full  and  per- 
fect relief  is  not  always  obtained  by  the  orthoptic  training 
of  the  interni,  prisms,  or  the  constant  use  of  glasses. 


STRABISMUS. 


CONDENSED   HISTORIES  OF  CASES  OF   EXOPHORIA. 


Vision  Age    Refrac.      Add.  Abd.  Tropometer      Operation 

first  ex.      in      out       tuck  ten 

No.  int.  ext. 

Rt.  Lt. 


Exoph.  Add.  Abd.  Glas-  Re- 

deg.      last    ex.     ses  mark 

before  years 

op.  after 


I 

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« 

EXOPHORIA.  73 

These  cases  taken  from  my  office  work  have  all  sub- 
mitted to  one  or  more  operations  as  needed.  They  show 
some  interesting  conditions  and  conclusions  in  reference 
to  the  prism  test  for  the  condition  of  exophoria.  I  par- 
ticularly wish  to  show  the  results  of  the  examinations  in 
the  field  of  fusion  as  I  consider  the  prism  test  in  this  field 
the  most  reliable  as  to  an  imbalance  of  the  ocular  muscles 
and  at  the  same  time  the  best  test  for  the  indications  for 
our  operations,  also  for  the  natural  balance  of  the  mus- 
cles of  the  eye.  The  operation  of  tenotomy  of  the 
externi  was  performed  much  oftener  than  the  oper- 
ation for  shortening  of  the  interni  with  the  catgut 
suture,  but  only  because  some  of  these  cases  were  oper- 
ated upon  before  I  commenced  to  do  the  shortening 
operation,  and  while  the  final  results  were  very  gratifying, 
in  many  of  these  cases,  at  the  present  time,  I  should 
prefer  the  shortening  of  the  interni  to  that  of  weakening 
the  opposing  muscle.  An  interesting  fact  in  connection 
with  these  tables  is  that  the  greater  portion  of  them  do 
not  show  myopic  refraction  as  nearly  three-fourths  of 
them  are  hyperopic  with  or  without  astigmatism.  The 
figures  for  the  field  of  fusion  are  the  final  ones,  that  is  to 
say,  the  results  of  the  examinations  of  adduction  and 
abduction  after  several  trials  with  the  prism  test  and  in 
which  there  was  no  increase  in  the  power  of  adduction  by 
the  exercise  of  the  interni.  They  compare  very  favorably 
with  Bannister's  tables.  The  visual  power  is  noted  by 
the  lower  figures  of  the  usual  notation  and  is  readily 
understood  by  adding  the  numerator  20  to  those  given 
in  the  tables,  as  70  indicates  V.  =  20/70,  and  15  indicates 


Explanation :  Visual  acuity,  the  numbers  are  the  denominator  with  20  as  the  nu- 
merator in  all  cases.  Prisms  were  used  in  some  cases  but  failed.  Results:  Two, 
failures.  Nineteen,  improved.  Thirty-nine,  decided  improvement.  Twenty-two, 
shortening  by  catgut  suture.  Twenty,  single  tenotomy.  Twenty-one,  both  externi 
tenotomized.  Three,  tenotomy  superior.  All  of  them  wore  glasses  for  a  reasonable 
time  and  the  visual  acuity  is  with  glasses.  Four  showed  hyperphoria. 


74 


STRABISMUS. 


20/15.,  etc.  In  the  other  columns  will  be  found  the 
refraction,  age,  operations,  tropometer  findings,  time 
elapsed  between  the  first  and  final  examinations,  and 
lastly  the  test  for  adduction  and  abduction  by  prisms. 
All  these  cases  show  exophoria  more  or  less  before  oper- 
ation and  orthophoria  after  the  final  examination. 

Paralysis  of  Convergence  :  Although  not  connected  with 
the  subject  of  this  work,  yet,  as  this  condition  may  be 
mistaken  for  a  slight  divergent  squint  or  exophoria,  I 
deem  it  necessary  to  mention  its  essential  features.  In 
the  discussion  of  exophoria  I  have  spoken  of  the  center 
for  convergence  and  of  its  location  and  of  its  action  on 
the  eyeballs,  in  which  we  find  that  it  controls  convergence 
of  the  visual  lines  from  the  first  position  to  that  of  the 
most  extreme  convergence  that  the  action  of  the  interni 
will  admit.  That  the  control  of  this  center  is  limited  to 
this  action  is  well  shown  in  the  cases  of  paralysis  of  this 
function,  as  we  find  very  slight,  if  any,  crossed  diplopia  — 
or  it  may  be  homonymous  —  there  is  no  appearance  of 
any  deviation  of  the  optic  axes,  though  in  some  cases  a 
slight  deviation  may  be  detected  under  an  examination 
with  the  perimeter.  The  slight  inability  to  fix  the  eyes 
inside  of  the  point  of  infinity  may  give  rise  to  some 
unsteadiness  in  walking.  In  the  field  of  version  we  find 
the  associated  movements  of  the  eyes  are  almost  per- 
fect. They  will  move  in  unison  to  all  parts  of  the  field, 
but  as  soon  as  the  test  object  is  brought  nearer  to  the 
eyes,  diplopia  commences  and  gradually  increases.  This 
shows  crossed  diplopia,  becoming  greater  as  the  object  is 
brought  closer,  and  if  the  eyes  are  watched  they  will  seem 
to  stand  at  the  first  position,  showing  no  power  to  con- 
verge. The  field  of  fusion  seems  to  be  abolished,  as 
adduction  and  abduction  will  be  very  low  in  degree,  possi- 
bly only  one  degree  in  each  direction.  All  this  will  cause 
a  complete  inability  to  read  or  to  see  near  objects,  as  they 


EXOPHORIA.  75 

cannot  fix  with  either  eye  an  object  held  in  the  median 
plane  of  the  head.  In  squint,  one  eye  will  always  fix  the 
object,  no  matter  where  it  is  held  and  the  vision  will  be 
steady.  An  attack  of  this  condition  generally  comes  on 
suddenly,  and  must  be  due  to  some  pathological  condition 
in  the  region  of  the  Aqueduct  of  Sylvius.  It  is  then  evi- 
dent that  the  cause  is  central,  and  the  only  treatment  that 
may  be  of  service  must  be  in  that  direction,  while  opera- 
tive interference  will  not  be  of  any  use. 

Paralysis  of  Divergence.  This  term  is  only  mentioned 
in  this  work  because  it  is  frequently  spoken  of  by  other 
writers  and  for  the  sake  of  completeness.  It  seems  to  be 
used  in  the  same  sense  as  that  of  insufficiency  of  divergence, 
but  the  last  named  term  is  simply  and  only  esophoria,  or 
weakness  of  the  externi.  In  my  conception  of  this  condi- 
tion at  the  present  time  I  must  state  that  the  condition 
of  paralysis  of  divergence  cannot  occur,  in  either  a  natural 
or  a  pathological  condition  of  the  eyes,  as  I  understand 
the  action  of  the  ocular  muscles.  I  have  only  seen  one 
case  reported,  that  by  Duane,  in  the  proceedings  of  the 
Ophthalmological  Section  of  the  Academy,  published  in 
the  Archives,  May  1903,  but  I  can  see  no  evidence  of  a 
paralysis  of  divergence  in  this  case. 

Divergence  of  the  eyes  —  as  I  understand  it,  and  as  I 
have  discussed  it  in  the  subject  of  the  movements  of  the 
eyes  —  consists  of  the  motion  outward  of  the  visual  lines, 
not  from  the  position  of  extreme  convergence,  as  some 
others  claim,  but  from  the  first  position  of  the  eyes,  when 
the  look  is  directed  forward  to  infinity,  on  or  slightly 
below  the  horizontal  plane  ;  or,  we  may  say,  in  other 
words,  the  position  of  the  optic  axes  in  complete  paralysis 
of  all  the  straight  muscles  of  the  eye,  ophthalmoplegia 
externa. 

Then  divergence  —  being  the  ability  of  the  eyes  to  move 
or  rotate  outward  from  this  first  position  would  place  the 


7  6  STRABISMUS. 

eyes  in  an  abnormal  position  or  in  a  position  that  is  not 
required  by  nature  and  cannot  exist  as  a  special  function  of 
the  eyes.  It  can  only  be  present  when  there  is  some  anom- 
aly of  the  ocular  muscles  or  when  the  condition  is  brought 
about  by  some  artificial  means,  as  by  the  action  of  prisms 
with  the  bases  placed  inward.  The  turning  outward  of 
the  eyes,  from  the  position  of  convergence,  is  not  diver- 
gence, but  simply  one  of  relaxation  of  the  interni  from 
the  stimulation  of  the  convergence  center,  with  the  eyes 
returning  to  the  natural  or  first  position,  and  no  require- 
ments of  nature  or  of  physics  will  ever  demand  that  the 
eyes  should  pass  beyond  that  position,  nor  has  any  evi- 
dence ever  been  presented,  as  far  as  my  information 
extends,  that  would  show  a  possible  center  for  that  con- 
trol or  necessity  for  any  function  of  that  nature.  The 
eyes  may  turn  out,  either  singly  or  combined,  under  the 
action  of  prisms  and  the  stimulation  for  fusion,  but  this  is 
shown  to  be  the  direct  action  of  the  externi,  as  demon- 
strated by  the  tests  for  abduction.  Hence,  because  we 
find  an  eye  that  from  weakness  of  the  externi  cannot  turn 
the  visual  line  outward  more  than  one  degree  of  prism  - 
the  same  as  we  meet  in  the  cases  of  esophoria  —  this  is  not 
paralysis  or  even  paresis  and  the  truth  of  this  proposition 
is  easily  demonstrated  by  the  examination  of  the  rotation 
of  the  eye  in  the  field  of  version.* 

I  am  inclined  to  think  it  would  be  better  to  eliminate 
the  term  of  "paralysis  of  divergence"  from  those  of  the 
motility  of  the  eyes,  at  least  until  some  more  positive 
evidence  has  been  shown  that  we  may  have  a  center  of 
the  brain  that  controls  this  function.  This  so-called  pa- 
ralysis or  esophoria  admits  of  operative  interference  and 
cure.  Its  opposite  or  true  paralysis  of  convergence  will 
not  be  improved  by  an  operation. 

*  See  article  by  Berry,  in  Trans.  Oph.  Soc.  of  the  United  Kingdom, 
Vol.  XXI. 


t.  OprnxFTT,  NUB. 


CHAPTER  VI. 

HYPERPHORIA    AND    HYPOPHORIA,    OR    LATENT    VERTICAL 

SQUINT. 

THESE  two  terms  signify  practically  the  same  condition 
of  the  visual  lines,  that  is  to  say,  a  condition  in  which  the 
visual  line  of  one  eye  tends  in  a  direction  above  the  visual 
line  of  the  other  eye.  This  vertical  tendency  may  exist 
in  only  one  eye  or  the  same  tendency  may  exist  to  the 
same  degree  in  each  eye.  This  condition  of  double  hyper- 
phoria  is  called  anaphoria  when  both  lines  tend  to  turn 
above,  and  kataphoria  when  both  lines  tend  to  turn 
below  the  plane  of  regard.  It  is  in  the  study  of  these 
tendencies  that  one  is  led  almost  positively  to  the  consid- 
eration of  the  muscular  origin  of  all  squint,  and  it  is  very 
difficult,  I  might  say  impossible,  to  find  a  dividing  line 
between  heterophoria  and  squint.  If  this  be  so  then  we 
must  consider  that  all  squint  is  simply  a  manifestation  of 
what  was  a  latent  condition.  This  is  well  illustrated  in 
hyperphoria,  in  which  cases  are  reported  of  one  degree 
up  to  ten  degree  or  more  and  when  beyond  that  then 
the  tendency  becomes  obvious,  although  they  may  have 
binocular  vision. 

Hyperphoria  and  hypophoria,  therefore,  as  the  terms 
imply,  denote  respectively  a  tendency  of  one  visual  line 
to  turn  above  or  below  that  of  the  other,  and  may  be  des- 
ignated as  right  or  left  according  to  the  eye  which  tends 
to  deviate  from  the  plane  of  regard.  Right  hyperphoria 
denotes  a  tendency  of  the  visual  line  of  the  right  eye  to 
turn  in  an  upward  direction,  so  that  direct  rays  of  light 


7$  STRABISMUS. 

will  fall  upon  the  upper  part  of  the  retinal  field  and  be 
projected  downward.  The  same  rule  will  apply  to  all 
other  deviations  as  proposed  in  the  classification  of  this 
condition.  These  tendencies  are  not  incompatible  with 
perfect  binocular  vision  as  long  as  the  fusion  power  is 
fairly  well  developed  and  with  good  illumination  of  the 
test  object ;  but  as  soon  as  we  reduce  the  fusion  power  by 
a  colored  glass,  or  the  rod  test,  then  the  latent  tendency 
becomes  manifest.  Diplopia  will  result  according  to  the 
anatomical  condition  of  the  muscular  structure  of  the  eye 
Hyperphoria  is  very  frequently  found  in  the  first  exami- 
nation of  asthenopic  cases,  particularly  if  the  diagnosis  is 
made  from  the  finding  of  the  rod  test  or  that  of  the  pho- 
rometer,  and  is  said  to  be  about  thirty  or  thirty-five  per 
cent,  of  all  the  cases.  This  is  a  statement  that  I  have  no 
wish  to  deny,  but  as  I  have  stated  before,  the  rod  and 
phorometer  tests  deprive  the  eyes  of  their  most  important 
and  controlling  function ;  consequently,  I  doubt  very 
much  if  we  can  rely  upon  a  diagnosis  made  in  this  man- 
ner. From  this  the  inference  is  very  obvious,  that  unless 
the  deviation  is  very  pronounced  —  five  or  more  degrees 
-we  may  disregard  any  slight  tendency  of  a  vertical 
deviation  when  the  fusion  force  of  the  eyes  is  abolished. 
The  etiology  of  all  these  conditions  of  vertical  imbalance 
of  the  eyes  rests  simply  on  the  power  of  certain  muscles 
to  turn  the  eyeball  in  a  vertical  direction,  and  not  on  the 
amount  of  innervation.  If  we  seek  for  the  primal  or 
fundamental  cause  I  think  we  will  find  it  in  an  essential 
weakness  of  certain  muscular  structures  that  should  tend 
to  keep  the  eyes  in  the  primary  position  when  the  fusion 
force  of  the  eyes  is  active.  "  It  is  a  local  physical  deform- 
ity," truly  idiopathic  and  manifested  by  a  weakness  of 
some  one  or  more  of  the  straight  muscles  of  the  eye. 
Innervation,  hypermetropia,  or  any  other  of  the  contrib- 
uting causes  of  squint  cannot  play  any  part  in  these  devi- 


HYPEKPHORIA  AND  HYPOPHORIA. 


79 


ations  ;  hence  a  vertical  tendency,  either  up  or  down,  is 
due  to  an  essential  weakness  of  one  of  the  muscles. 

To  particularize  this  condition,  we  have  in  hyperphoria 
a  weakness  of  one  of  the  depressors  of  the  eyeball,  an 
inferior  rectus  ;  in  hypophoria,  a  weakness  of  one  of  the 
elevators  of  the  eyeball,  a  superior  rectus  ;  in  anaphoria, 
a  weakness  of  both  inferior  recti  ;  and  similarly,  in  kata- 
phoria,  a  weakness  of  both  elevators.  It  is  possible  that 
we  may  find  the  reason  for  these  deviations  in  an  over- 
action  of  the  muscles,  but  I  prefer  to  consider  the  funda- 
mental cause  to  be  one  of  weakness,  or  deficient  power 
in  the  anatomical  construction  or  insertion  of  the  muscles, 
for  the  reason  that  has  been  explained. 

The  symptoms  of  hyperphoria  or  hypophoria  are  very 
similar  to  those  of  the  other  forms  of  heterophoria  —  pain 
in  the  head  being  the  most  prominent ;  sometimes  extend- 
ing backward  to  the  occiput,  with  dizziness  and  nausea, 
and  frequently  felt  in  the  mornings  on  waking  from  sleep. 
Irritation,  with  congestion  of  the  conjunctiva,  is  frequently 
present,  and  diploplia  may  be  occasionally  noted.  The 
habit  of  tipping  the  head  is  sometimes  noticed  in  hyper- 
phoria, so  much  so  in  some  cases  as  to  resemble  wryneck 
or  torticollis.  In  cases  of  anaphoria  or  its  opposite,  kata- 
phoria,  we  have  a  tipping  of  the  head  either  backwards  or 
.forwards.  In  anaphoria  with  a  weakness  of  the  inferior 
recti,  both  visual  lines  tend  to  deviate  upward,  the  head 
is  thrown  forward  to  relieve  the  strain  on  the  weak  mus- 
cles, with  contraction  of  the  anterior  portion  of  the  occipito- 
frontalis,  causing  a  constant  scowl  on  the  face.  These 
cases  are  very  miserable  until  the  imbalance  is  corrected. 

Diagnosis.  From  what  I  have  stated  in  reference  to  the 
reliability  of  the  different  examinations  for  heterophoria 
and  squint,  there  are  only  two  tests  that  can  be  fully  de- 
pended upon  for  the  diagnosis  of  these  vertical  tendencies, 
all  others  being  complementary.  No  operation  should  be 


8o  STRABISMUS. 

performed  until  these  two  tests  fully  agree  upon  repeated 
examinations!  In  vertical  squint  —  hypertropia  —  the 
condition  is  obvious,  but  though  we  may  note  that  the 
direction  of  the  opposite  axis  is  above  that  of  the  fellow 
eye,  yet  we  must  decide  as  to  the  rotational  power  of  the 
muscles  before  we  can  have  positive  indications  for  our 
operative  interference. 

To  illustrate  the  method  of  diagnosis  in  all  vertical 
tendencies  I  will  give  the  examination  of  the  muscular 
condition  of  certain  cases  that  will  make  the  indication 
clear  and  the  diagnosis  to  be  readily  understood. 

Miss  R.  C. ,  age  15.  Refraction  Hy.  with  Ah.  90°,  said  to  have 
had  convergent  squint  when  a  child,  but  at  present  the  visual  lines 
seem  normal.  Adduction  R.  10°,  L.  12°.  Abduction  R.  and  L.  5°. 
This  duction  test  shows  weak  externi  as  the  power  of  adduction  may 
increase  by  testing.  Supraduction,  R.  i°,  L.  3°.  This  vertical 
test  for  duction  shows  a  decided  tendency  for  the  left  visual  line  to 
tend  upwards,  at  the  same  time  the  fusion  force  is  fairly  good.  Tro- 
pometer,  R,  30°  up  ;  60  down  ;  50°  in  ;  60°  out.  L.  40°  up  ;  45° 
down  ;  60°  in  ;  45  °  out. 

In  this  examination  with  the  tropometer  we  have  a  clear 
exposition  of  the  imbalance  of  the  ocular  muscles  in  the  left 
eye  almost  identical  with  that  of  the  prism  test,  as  this  case 
shows  the  vertical  tendency  upward  of  the  left  eye  from 
weakness  of  the  inferior,  and  a  tendency  to  esophoria  in  the 
same  eye.  The  inference  is  plain  in  this  case  that  the  child 
probably  did  have  convergent  squint  of  the  left  eye,  but  as 
the  fusion  force  ^became  more  fully  developed  with  age  the 
visual  lines  have  become  adjusted,  binocular  vision  is  re- 
established, and  there  is  no  evidence  of  squint.  This  case 
well  illustrates  the  power  of  the  fusion  force  as  a  contribut- 
ing cause  of  squint,  with  a  tendency  of  the  eyes  to  look  to 
the  right,  not  shown  in  true  lateral  squint,  and  the  reason 
for  the  old  story  "  the  child  will  outgrow  its  squint." 


HYPERPHORIA  AND  HYPOPHORIA.  8 1 

Another  similar  case,  but  more  pronounced,  that  cannot 
outgrow  the  squint,  is  the  following  : 

Master  R.  A.  F.,  age  14,  has  a  fixed  upward  squint  of  the  left  eye, 
deviating  about  two  millimeters.  V,=2o/i5  each,  no  glasses  ac- 
cepted, possibly  +.  50.  cyl.  ax,  90°.  No  binocular  vision,  and  con- 
sequently no  fusion  test  with  prisms. 

Tropometer=R.  30°  up;  55°    down;    50°  in;  50°   out. 
=  L.  45  °  up  ;  40  °   down  ;    60  °  in  ;  45  °    out. 

Here  again  we  find  a  clear,  positive  indication  ol  a  mus- 
cular imbalance,  similar  to  the  one  first  mentioned,  but  we 
also  notice  the  extreme  weakness  of  the  left  inferior ;  hence 
though  the  boy  has  a  similar  imbalance,  his  squint  remains 
permanent.  In  this  case  I  shortened  the  inferior — no  in- 
dication for  tenotomy  here  — with  the  following  result  : 

Tropometer.  R.  35  c  up  ;  50°  down.  L.  30  up  ;  40°  down.  Lat- 
eral balance  same  as  at  first.  Subduction  4°  each.  This  boy  has 
binocular  vision  at  20  feet  and  with  the  stereoscope. 

Third  case.  Mr.  T.  H.,  age  39.  This  man  has  suffered  for  a 
long  time  with  a  constant  tendency  to  scowl  and  to  hold  the  head 
forward,  as  he  can  see  better  in  this  position.  He  has  constant  pain 
in  the  head  and  photophobia.  V.  =20/50  w.  -+-  50.=  20/20  each. 
Adduction  10°  ;  abduction  4°;  supraduction  i°  each.  His  vertical 
rotation  measured  by  the  perimeter  shows  right  eye  up  33°;  down 
20°;  left  eye  up  40°  ;  down  20°.  By  the 

Tropometer  =R.  30°  up;  45°  down;  50°  in;  50°  out. 
"  =L.  30°  up  ;  40°  down;  50°  in  ;  50°  out. 

His  lateral  movements  of  the  eyes  were  normal.  In 
this  case,  as  the  superior  seemed  to  be  so  powerful,  I 
did  a  complete  tenotomy  of  both  elevators,  with  complete 
and  permanent  relief  of  all  symptoms,  and  the  objective 
examination  was  as  follows, —  tropometer,  each  eye,  up 
25°  and  down  50°  ;  lateral  balance  the  same  as  before. 
Here  I  considered  that  a  tenotomy  of  both  superior  recti 
would  correct  the  condition  better  than  a  shortening  of 
the  inferior. 


82  STRABISMUS. 

In  the  consideration  of  hyperphoria,  an  important  ques- 
tion arises  as  to  the  influence  that  this  condition  may 
have  on  the  lateral  balance  of  the  ocular  muscles. 
Stevens  at  one  time  claimed  that  all  lateral  imbalance  and 
even  fixed  squint  was  due  more  to  a  vertical  tendency  of 
the  ocular  muscle  than  to  any  lateral  deviation  that  may 
be  present.  While  I  cannot  agree  with  this  suggestion  — 
as  in  many  cases  I  have  seen  a  vertical  tendency  disap- 
pear under  the  correction  of  a  lateral  imbalance  by  an 
operation  —  yet  the  vertical  balance  of  the  eyes  is  very 
important,  and  should  be  carefully  considered  in  all  our 
cases.  This  is  well  shown  in  the  test  with  prisms,  as  in 
the  estimation  of  adduction  and  abduction  it  is  very 
•essential  that  the  prisms  should  be  held  or  placed  in  the 
frame  perfectly  horizontal,  particularly  so  when  using  the 
higher  degrees.  The  slightest  tipping  of  the  apex  of 
the  prism  will  so  deviate  the  image  of  the  test  object 
beyond  the  slight  power  of  the  vertical  acting  muscles, 
that  the  images  will  not  fuse,  but  they  will  readily  do  so 
when  the  images  are  perfectly  level.  It  is,  therefore, 
necessary  to  see  that  the  images  are  on  the  same  plane  if 
we  would  find  out  the  true  power  of  rotation  of  an  eye  in 
the  horizontal  plane. 

The  power  to  turn  the  eyes  up  or  down  under  the  fu- 
sion force  is  very  low,  only  from  one  to  three  degrees,  and 
this  function  may  be  very  easily  disturbed  in  the  presence 
of  a  lateral  tendency.  Many  cases  will  show  a  much  larger 
power  to  rotate  in  the  horizontal  plane  by  careful  attention 
to  this  point.  On  the  other  hand,  the  necessity  of  hold- 
ing the  prism  perfectly  vertical  in  testing  superduction  and 
subduction  is  not  so  necessary  owing  to  the  greater  power 
of  the  lateral  moving  muscles. 

In  many  cases  we  may  have  a  vertical  tendency  associ- 
ated with  a  lateral  deviation,  and  the  question  arises  as  to 
which  condition  should  be  first  corrected.  The  answer  to 


HYPEKPHORIA  AND  HYPOPHORIA.  83 

this  will  depend  upon  the  degree  of  deviation  or  tendency 
in  each  direction.  In  other  words,  if  we  have  a  decided 
vertical  tendency  to  deviation,  then  this  condition  should 
be  corrected  first.  If  I  find  by  the  rod  test  a  vertical 
tendency  of  three  or  more  degrees,  I  would  give  this  very 
careful  attention,  and  in  this  consideration  we  have  the 
very  important  question  —  where  is  the  essential  fault  ? 
Is  it  in  the  superior  or  the  inferior  that  the  weakness  may 
be  found  ?  The  test  with  the  rod  will  not  show  it,  nor  that 
of  the  phorometer,  but  it  can  be  well  demonstrated  by  the 
careful  test  with  prisms.  This  must  be  and  can  be  scientifi- 
cally confirmed  by  the  tropometer.  The  measurements 
by  this  instrument  are  very  exact  and  at  once  indicate  the 
muscle  that  is  essentially  too  strong,  or  the  one  that  is 
essentially  too  weak.  A  decided  rotation  upward  of  less 
than  30°  will  show  weakness  of  the  upward  turning ;  and 
downward,  if  less  than  50°  will  show  a  weakness  of  the 
down  turning. 

Furthermore,  if  we  do  find  a  deficiency  of  power  in  the 
vertical  acting  muscles,  then  the  consideration  is  presented 
which  muscle  shall  be  corrected?  In  other  words,  is  it 
more  important  to  weaken  a  strong  superior  recti  or  to 
strengthen  a  weak  inferior  recti  ?  It  goes  without  saying 
that  one  of  the  most  important  functions  in  the  field  of 
version  is  that  of  looking  downward,  as  in  all  our  work 
the  visual  lines  must  be  carried  and  held  below  the 
horizontal  plane.  For  this  reason,  unless  the  upward 
tendency  is  very  great,  I  prefer  to  make  the  muscle  of 
subduction  stronger  by  the  operation  of  shortening  the 
inferior  to  that  of  weakening  the  opposing  superior  rectus. 
A  case  that  will  show  a  vertical  tendency,  in  which  we 
find  the  lateral  fusion  force  in  the  proportions  of  one  of 
abduction  to  two  or  three  of  adduction,  will  always  be 
improved  by  a  correction  of  the  hyperphoria,  but  in  my 
experience,  if  the  lateral  muscles  show  an  imbalance  of 


84  STRABISMUS. 

one  of  abduction  to  one  of  adduction  (exophoria),  or  one 
of  abduction  to  four  or  more  of  adduction  (esophoria), 
then  we  may  correct  these  conditions,  even  in  the  presence 
of  a  slight  vertical  tendency,  with  almost  positive  assurance 
of  success. 

There  are  still  other  cases  that  may  come  under  this 
classification,  not  infrequent,  in  which  we  have  a  tendency 
of  both  visual  lines  to  turn  the  same  way  but  laterally,  in 
other  words,  they  tend  to  look  to  the  right  or  left.  I 
have  no  terms  to  express  this  condition  nor  do  I  think 
any  have  been  suggested,  but  these  cases  are  occasionally 
met  with  in  an  examination,  and  Stevens  has  suggested 
that  it  is  due  to  a  condition  of  cyclophoria.  I  have  not 
convinced  myself  that  that  suggestion  is  correct  but  I  am 
inclined  to  look  upon  all  these  cases  as  due  to  the  same 
conditions  as  in  all  other  cases  of  squint,  that  is  to  say,  we 
have  an  essential  weakness  of  one  internus  associated  with 
a  similar  weakness  of  one  externus,  hence  the  tendency 
to  look  in  one  of  the  two  lateral  directions. 

The  diagnosis  of  this  condition  can  only  be  made  in  the 
field  of  version,  as  shown  by  the  tropometer  or  possibly 
by  the  examination  with  the  perimeter.  I  will  illustrate 
this  by  two  cases. 

Mrs.  A.  J.  S.,  age  42.  V.  =  20/15.  Hm. -f-i.  D.  Glasses  assist  her 
very  much  but  still  she  has  some  pain  in  the  back  of  the  head  and 
neck.  Add.  12°;  Abd.  10°.  Rod,  esophoria. 

Tropometer  =R.  30°  up;   60°  down;  40°  in;  50°   out. 
"  =L.  30°  up  ;    60°  down  ;  50°  in  ;  40°   out. 

It  is  evident  that  the  right  eye  shows  a  tendency  to  turn 
outward  and  the  left  eye  to  turn  inward  ;  in  other  words, 
a  tendency  to  look  to  the  right.  We  also  note  that  the 
prism  test  shows  exophoria  and  the  rod  test  esophoria. 

Another  case  : 

Miss  H.  D.,  age  24.  V.=2o/i5.  Ah.  90°,  Her  sister  states  that 
this  young  lady  is  always  looking  to  the  right. 


HYPERPHORIA  AND  HYPOPHORIA.  85 

Tropometer=R.  30°  up;  50°  down  ;  50°  in  ;  55°  out. 
"          =L.  30°  up  ;  56°  down  ;  62°  in  ;  50°  out. 

It  seems  to  me  that  the  treatment  of  these  cases  is  the 
same  as  in  all  other  cases  of  imbalance,  according  to  the 
indications,  as  by  a  tenotomy,  partial  or  complete,  or  by  a 
shortening  if  needed  after  the  correction  of  the  refraction. 
In  these  cases  the  prism  test  of  the  fusion  force  will  not 
indicate  the  imbalance  as  the  slightest  turning  of  the  head 
will  place  the  eyes  in  such  a  position  that  the  relation  of 
adduction  and  abduction  may  be  almost  normal.  The 
rod  test  may  give  us  some  indication  of  an  imbalance,  as 
in  one  of  the  above  cases  we  had  an  esophoria  of  7°  that 
was  completely  corrected  by  a  shortening  of  one  of  the 
externi. 

Cyclophoria.  It  does  not  seem  to  me  that  this  work 
will  be  complete  without  a  description  of  this  anomalous 
condition  of  the  ocular  muscles ;  although  it  does  not  pro- 
duce a  squint,  it  may  complicate  an  imbalance.  It  is  very 
seldom  met  in  the  examinations,  and  if  present  is  probably 
due  to  a  paresis  of  one  of  the  obliques.  Savage  and  also 
Stevens  seem  to  place  very  great  reliance  on  the  influence 
of  torsion  in  the  estimation  of  an  imbalance  of  the  ocular 
muscles,  but  as  far  as  my  own  examinations  show  I  have 
failed  to  find  it,  unless  associated  with  an  astigmatism 
with  oblique  axes  or  with  some  other  condition  of  hetero- 
phoria,  the  correction  of  which  has  seemed  to  correct  the 
fault  in  the  torsion  of  the  eyes.  As  the  term  is  expressed 
it  represents  a  tendency  of  the  eyeball  to  turn  on  the  optic 
axis,  the  upper  part  of  the  vertical  meridian  tending  to 
turn,  either  outward  or  inward,  in  reference  to  the  median 
plane  of  the  head  or  to  each  other. 

The  necessity  to  keep  the  vertical  plane  of  one  eye  par- 
allel to  that  of  the  other  or  to  the  median  plane  of  the  head 
in  all  the  movements  of  the  eyes  in  the  binocular  fields  of 
vision  is  too  obvious  to  need  any  explanation.  Its 


86 


STRABISMUS. 


importance  in  the  act  of  binocular  vision  is  very  great,  yet 
it  seems  to  me  that  the  necessary  power  to  rotate  the  eye 
about  the  optic  axis  is  very  slight  and  consequently  the 
liability  of  any  disturbance  from  this  cause  can  be  almost 
neglected.  The  terms  suggested  to  denote  this  condition 
are :  Plus  Cyclophoria,  by  Price ;  Plus  Declination,  by 
Stevens  ;  and  Plus  Torsion  by  Maddox,  when  the  verti- 
cal axes  of  the  eyes  tend  to  turn  away  from  the  vertical 
plane  of  the  head.  When  the  vertical  axes  tend  to  turn 
toward  the  median  plane  we  have  Minus  Cyclophoria,  etc. 
It  is  to  be  regretted  that  these  writers  did  not  select  the 
same  terms,  but  I  think  that  of  Price  is  the  best  as 
expressing  the  conditions. 

'Diagnosis.     For  this  purpose  a  Maddox  double  prism 

with  the  bases  horizontal  and 
the  test  object  a  line  on  a  white 
cardboard  is  used,  when  test- 
ing this  function  at  the  reading 
distance  or  about  twelve  inches. 
This  prism,  when  placed  over  the 
one  eye,  will  cause  the  line  to 
be  seen  double  and  the  line  that 
MADDOX  DOUBLE  PRISM.  is  seen  with  the  other  eye  will 
be  found  between  the  others.  If  all  three  lines  are  seen 
parallel  there  is  no  tendency  to  Cyclophoria,  but  if  the 
central  line  tends  to  tip  in  any  direction  there  may  be 
some  weakness  of  the  obliques.  The  appearance  of  these 
lines  in  the  various  types  of  Cyclophoria  is  shown  in  this 
diagram. 


HYPERPHORIA  AND  HYPOPHORIA.  8/ 

Position  of  the  lines  in  a  under-action  of  the  left  sup.  oblique 
"  "  "      "    b  "  "         left  inf.  oblique 

"  "  "      "    c  "  "          right  sup.  oblique 

"  "  "      "    d  "  "          right  inf.  oblique 

The  clinoscope,  improved  by  Stevens,  is  an  excellent 
instrument  for  the  diagnosis  of  any  weakness  or  paresis  of 
the  oblique  muscles.  It  is  shown  in  the  illustration. 


ILLUSTRATION  OF  CLINOSCOPE  —  STEVENS*  LATEST  MODEL. 

The  description  for  the  use  of  this  instrument  is  as  fol- 
lows :  "  The  discs  with  a  single  pin,  with  the  head  in  the 
center,  drawn  on  each  should  be  placed  so  that  the  point 
may  be  up  for  one  eye  and  down  for  the  other.  Each 
pin  should  be  vertical  and  the  instrument  so  adjusted  as 
to  allow  easy  fusion  of  the  heads  of  the  pins.  When  the 
two  discs  appear  as  one  the  two  pins  should  be  the  verti- 
cal diameter  of  the  fused  discs.  If  the  one  pin  is  a  radius 
pointing  in  one  direction  obliquely,  and  the  other  is  a 
radius  pointing  obliquely  in  the  other  direction  (one 
toward  the  right  and  the  other  toward  the  left,  making 
an  oblique  diameter)  there  is  plus  cyclophoria  of  one  eye 
and  minus  cyclophoria  of  the  other.  If  the  upper  pin  is 
seen  by  the  left  eye  and  the  lower  pin  is  seen  by  the  right 
eye,  the  two  pins  pointing  to  the  right  would  show  plus 
cyclophoria  ;  while  minus  cyclophoria  would  be  shown  by 
the  two  pins  pointing  to  the  left.  If  the  top  pin  is  verti- 


88  STRABISMUS. 

cal  and  the  bottom  one  points  to  the  right  there  is  plus 
cyclophoria  of  the  right  eye  alone,  or  if  the  bottom  pin 
points  to  the  left  while  the  top  one  is  vertical  there  is 
minus  cyclophoria  of  the  right  eye  alone,  etc.  When  the 
pins  are  oblique  the  tubes  to  which  the  discs  are  fastened 
should  be  revolved  until  the  two  pins  are  vertical,  forming 
apparently  the  vertical  diameter  of  the  fused  discs.  The 
index  connected  with  each  tube  will  point  to  the  mark  on 
each  scale  indicating  the  quantity  of  error  in  each  eye." 
The  treatment  of  these  cases  of  cyclophoria  may  be  by 
the  rotation  of  cylindric  glasses  when  there  is  oblique 
astigmatism,  by  the  use  of  displaced  cylinders,  or  by  an 
operation  on  the  tendons  of  the  straight  muscles.  While 
the  writers  on  this  subject  claim  some  very  good  results  I 
have  not  had  sufficient  experience  with  their  methods  to 
advise  its  use. 

All  these  varieties  of  imbalance,  both  vertical  and  hori- 
zontal, may  be  manifest  or  latent ;  that  is  to  say,  they  may 
be  manifest  at  the  first  examination  or  may  be  demon- 
strated by  persistent  trials  of  the  action  of  the  muscles. 
I  have  not  found  it  necessary  to  make  this  distinction  in 
my  cases,  as  I  think  the  present  method  of  examination 
should  fully  develop  any  latent  error  in  the  balance  of 
the  ocular  muscles  that  may  be  present.  The  constant 
testing  of  the  interni  may  show  an  increased  power  of 
adduction,  and  the  wearing  of  prisms,  bases  in  or  out,  may 
develop  an  exophoria  or  an  esophoria,  but  I  do  not  think 
these  procedures  will  change  the  rotation  in  the  field  of 
version.  It  is  by  the  combination  of  all  the  true  and  con- 
firmatory tests  Chat  we  may  arrive  at  an  exact  conclusion 
as  to  the  imbalance  of  the  ocular  muscle  with  two  or 
three  examinations,  and  then  we  may  direct  our  treat- 
ment or  operation  as  indicated  by  these  tests. 


CHAPTER  VII. 

STRABISMUS    OR    HETEROTROPIA  :    CONCOMITANT    OR 
FUNCTIONAL. 

THE  extremely  interesting  paper  on  "  The  Etiology 
and  Educative  Treatment  of  Convergent  Strabismus,"  by 
Priestly  Smith,  M.  R.  C.  S.,  reviewed  in  the  Ophthalmic 
Record,  from  the  British  Medical  Journal,  July  2,  1898, 
points  to  the  innervation  theory  of  squint  for  its  etiology, 
as  he  states  that  "convergent  strabismus  is  a  disorder  of 
innervation  in  which  the  visual  centers  fail  to  control  the 
act  of  convergence,"  and  also  dwells  on  the  old  theory  of 
relative  hypermetropia  with  its  influence  on  accommoda- 
tion and  convergence,  thus  placing  all  cases  in  the  same 
uncertain  etiology. 

Bonders'  antithesis  is  as  follows :  "  Hypermetropia 
causes  accommodative  asthenopia,  to  be  actively  overcome 
by  strabismus  convergens.  Myopia,  to  muscular  astheno- 
pia, passively  yielding  to  strabismus  divergens."  A  very 
beautiful  theory,  which  has  found  many  admirers  and  dis- 
ciples ;  but  how  many  cases  do  we  meet  that  completely 
refute  and  demolish  these  propositions  ? 

Hansen  Grut,  in  his  prize  Essay,  advances  the  innerva- 
tion theory  for  his  cases  of  convergent  squint,  the  position 
of  rest  for  his  divergent  cases,  and  suggests  that  after 
death  or  in  full  ether  narcosis,  the  eyes  diverge  ;  but  in 
reference  to  this  Schweigger  says,  he  knows  that  neither 
"death  nor  narcosis  is  the  natural  condition  of  man." 

My  friend,  Dr.  A.  A.  Hubbell,  has  also  advanced  the 
innervation  theory  as  his  consideration  of  the  "  Patho- 


go  STRABISMUS. 

genesis  of  Concomitant  Strabismus,"  N.  Y.  State  Medical 
Association,  1901,  from  which  I  quote  :  "At  the  outset  I 
wish  to  define  concomitant  strabismus  as  a  disturbance  of 
oculo-motor  innervation,  accompanied  by  a  perceptible 
deviation  in  any  direction  of  the  visual  axis  of  one  eye 
from  the  point  of  fixation  of  the  visual  line  of  the  other 
eye." 

Walfors  says:  "  In  my  opinion  squint  depends  upon  an 
antecedent  anomaly  of  the  muscles,  in  which,  under  the 
influence  of  several  accompanying  factors,  among  which 
innervation  plays  an  important  part,  carries  the  eye  into  a 
squinting  position."  I  regret  that  I  am  not  acquainted 
with  Walfors'  theory  in  full,  but  it  seems  to  me  that  the 
first  part  of  his  proposition  may  lead  us  to  a  true  theory. 

Schweigger's  articles  do  not  seem  to  advance  any  par- 
ticular theory,  unless  it  is  that  of  Donders,  but  refers  to 
all  in  a  general  way,  while  Landolt  also  seems  to  hold  to 
the  antithesis  of  Donders. 

Worth,  on  "  Squint,"  P.  Blakiston&  Co.,  1903,  seems  to 
place  all  his  theory  of  the  cause  of  squint  on  the  loss  of  the 
fusion  power,  and  claims  certain  results  from  the  use  of 
his  amblyoscope,  by  which  he  has  corrected  a  certain  per- 
centage of  cases ;  but  it  seems  to  me  that  the  per  cent,  of 
correction  is  about  the  same  as  that  obtained  with  the  use 
of  glasses.  He  states  (p.  168)  :  "  Heterophoria  may  be  due 
to  a  muscle  or  group  of  muscles  being  too  weak  or  too 
strong  for  the  opponents  or  the  abnormal  insertion  of  a 
tendon.  .  .  heterophoria  is  essentially  a"  motor  anomaly,  but 
'Squint,'  on  the  other  hand,  is  essentially  due  to  a  defect 
in  the  fusion  faculty.  In  the  presence  of  this  fundamental 
cause,  heterophoria  may  give  rise  to  a  permanent  squint ; 
not  otherwise."  Here,  we  have  two  causes  for  what  is 
essentially  the  same  condition,  as  numerous  writers  con- 
sider fixed  squint  a  greater  degree  of  heterophoria.  Fur- 
thermore, Worth  says,  in  reference  to  the  muscle  theory, 


STRABISMUS  OR  HETEROTROPIA.  gi 

"  It  may  seem  reasonable  to  attribute  this  deformity  to  a 
defect  in  the  muscles  which  move  the  eyes.  A  little  in- 
vestigation ought  to  convince  any  one  of  the  falsity  of  this 
view."  I  quote  this  because  twenty  years'  investigation 
has  not  convinced  me;  and  I  find  that  Worth  bases  his 
reasons  why  the  muscles  are  not  at  fault  on  the  ability  of 
the  eyes  to  follow  the  finger  or  pencil  in  the  field  of  ver- 
sion and  then  to  note  the  corneal  edge  in  reference  to  the 
outer  canthus,  etc  He  claims  81  per  cent,  perfect  by  this 
test  but  had  he  made  the  examination  with  the  tropome- 
ter  —  a  much  more  exact  and  scientific  method  —  he  would 
have  found  a  deficiency  in  the  field  opposite  to  the  devia- 
tion of  the  squint  in  every  one  of  his  cases  or  one  hundred 
per  cent.  That  is  the  result  of  all  my  examinations. 

All  these  writers  have  advanced  their  ideas  on  the  sub- 
ject of  the  causes  of  squint,  and  one  writer  will  directly 
oppose  the  theory  of  another,  so  that  when  one  reads  the 
diverse  opinions  of  such  eminent  men  in  the  profession  of 
ophthalmology  he  feels  somewhat  at  a  loss  to  understand 
what  are  the  true  causes  of  squint. 

Every  physician  must  form  his  own  opinion  of  the  exist- 
ing condition  of  the  human  body,  either  pathological  or 
functional,  from  his  individual  experience  in  the  results  of 
his  cases,  and  to  formulate  a  theory  must  take  many  years 
of  constant  observation,  together  with  a  large  number  of 
illustrative  cases.  Hence,  any  theory  must  be  so  advanced 
that  it  may  meet  the  indications  in  all  cases,  even  though 
we  may  grant  the  proposition  that  "the  exception  proves 
the  rule." 

For  several  years  I  have  watched,  in  all  their  varying 
conditions,  my  cases  of  strabismus,  and  I  have  felt  that  I 
could  see  and  note  a  cause  and  effect  based  on  the  propo- 
sition which  has  been  stated  in  a  previous  paper  and  fur- 
ther improved  on  by  subsequent  observations,  as  follows : 
That  the  eyes  move  under  the  innervation  derived  from 


92  STRABISMUS. 

two  centers  of  the  brain  —  first,  in  the  field  of  fixation, 
(controlled  by  the  higher  centers  of  the  brain),  in  which 
all  the  straight  muscles  of  the  eye  are  capable  of  receiving 
nearly  the  same  amount  of  innervation,  and  consequently, 
under  the  stimulation  of  the  will-power  turn  the  eyes 
equally,  or  nearly  so,  in  all  parts  of  the  field  of  fixation  ; 
second,  that  the  eyes  rotate  in  the  field  of  fusion,  in  vari- 
ous degrees,  in  which  they  do  not  move  under  the  direct 
control  of  the  will-power,  but  about  a  common  point,  in 
certain  directions,  under  the  stimulation  of  a  center,  con- 
trolled by  the  automatic  action  of  the  brain.  This  func- 
tion is  not  influenced  by  the  action  of  the  will.  This  is 
called  "  unconscious  innervation,"  and  these  centers  receive 
"their  stimulation  from  the  desire  for  fusion  of  the  images 
on  the  retina.  These  movements  seem  to  be  controlled 
by  the  relative  power  of  the  straight  muscles,  as  shown  by 
their  size  and  their  insertion  into  the  sclera. 

Granting  the  above  conditions  as  existing  and  control- 
ling the  movements  of  the  eyes  and  the  direction  of  the 
visual  lines,  we  may  construct  a  theory  that  will  elucidate 
and  explain  the  causes  of  all  conditions  of  strabismus. 

Hansell,  of  Philadelphia,  says :  "  It  is  unscientific  to  at- 
tempt to  separate  the  muscular  from  the  innervational  ap- 
paratus, the  more  so  as  the  latter  comprises  both  the  fusion 
force  and  the  impluse  conveyed  by  the  nerve  trunks  ;  and 
equally  futile  is  it  to  speak  of  one  muscle  as  having  more 
power,  as  measured  by  prisms,  than  its  corresponding 
muscle  in  the  other  eye."  Having  read  this,  I  turn  to 
Stevens  and  find :  "  All  these  determinations  having  been 
made  with  sufficient  care  (that  is,  the  equilibrium  test, 
etc.),  the  examiner  proceeds  to  ascertain  the  relative 
power  of  the  different  pairs  of  muscles  by  finding  the 
strongest  prism  with  which  images  can  be  united  in  differ- 
ent directions."  If,  then,  the  prism  test  is  unscientific  and 
useless,  why  use  it  at  all?  In  my  opinion  it  is  one  of  the 


STRABISMUS  OR  HETEROTROPIA. 


93 


reliable  tests  for  the  relative  power  and  the  indications  of 
a  muscular  anomaly. 

May  not  a  theory  then,  depend  upon  the  muscular  con- 
ditions of  the  eyes  essentially,  and  which  may  be  associ- 
ated with  certain  other  conditions  in  the  eyes  themselves  ; 
in  other  words,  may  not  the  position  of  the  visual  lines 
depend  upon  the  fusion  power,  or  guiding  sensation  of  the 
eyes,  and  the  relative  power  of  the  straight  muscles? 

If  we  study  the  theories  and  the  propositions  as 
advanced  for  the  causation  of  squint,  all  cases  must  be 
placed  under  one  head  or  class,  dividing  them  simply 
according  to  degree,  as  latent,  periodic,  and  fixed ;  and, 
though  the  majority  of  writers  apply  the  same  theory  to 
all  alike,  to  my  mind,  and  because  of  my  experience, 
there  seem  to  be  two  distinct  classes,  with  their  respective 
conditions,  that  tend  to  cause  the  squint,  but  with  one 
underlying  cause  in  all  cases.  Into  these  two  classes  we 
may  divide  all  our  cases  of  squint,  then  proceed  to  develop 
a  theory  that  will  cover  both  classes  in  which  the  relative 
power  of  the  straight  muscles  of  the  eye  must  and  do  play 
the  most  important  part. 

Then,  as  I  have  always  claimed  (and  I  note  that  other 
writers  are  now  alluding  to  it)  we  must  take  into  consid- 
eration the  guiding  sensation  of  the  eyes,  the  essential 
fusion  power  with  other  contributing  conditions,  if  we 
would  find  a  reasonable  cause  for  squint  and  its  depend- 
ence on  the  relative  power  of  the  muscles. 

Before  proceeding  further  with  the  argument,  let  me, 
in  a  few  words,  give  the  conditions  of  two  cases  of  squint 
found  in  girls  of  the  same  family. 

Rebecca  L.,  age  14,  convergent  concomitant  squint, 
fixed  in  the  left  eye,  onset  when  one  year  old.  R.  E.  V. 
=i§,  L.  E.  V.=^°o,  Ah.=i.D.  ax.  90°  in  each  eye.  Oph- 
thalmoscope and  retinoscope  show  the  same  refractive 
condition.  Operation,  tenotomy  on  the  left  internus, 


94 


STRABISMUS. 


when  seven  years  old,  or  seven  years  ago.  To-day  there 
is  no  evidence  of  the  squint,  the  cosmetic  effect  is  very 
good,  the  visual  axes  seem  parallel,  and  she  seems  to  fix 
with  both  eyes  at  the  near  point,  yet  the  visual  power  is 
the  same  as  at  the  first  examination.  Her  sister  Edith 
L.,  age  n,  convergent  concomitant  squint,  nearly  always 
fixed  in  the  right  eye,  onset  when  six  years  old.  V.=i§ 
in  each  eye,  Hm.  1.50  D.  in  each  eye.  No  astigmatism. 
Ophthalmoscope  and  retinoscope  show  about  5  D.  of 
hyperopia.  Has  homonymous  diplopia  of  30°.  Glasses 
were  ordered  for  this  case  with  complete  disappearance  of 
the  squint. 

I  would  also  call  attention  to  a  case  of  divergent  squint 
-that  I  operated  on  a  very  short  time  ago,  when  on  the 
exposure  of  the  tendon  of  the  internus  it  was  found  to  be 
very  small,  not  more  than  I  of  an  inch  broad ;  while  the 
externus  of  the  same  eye  was  found  to  be  more  than  J  of 
an  inch  broad.  This  is  pretty  strong  evidence  of  the 
muscular  action  on  the  cause  of  squint. 

Now,  it  seems  to  me,  when  we  compare  the  clinical  his- 
tory and  the  result  of  treatment  in  the  two  cases  reported 
above  there  must  be  some  cause  acting  in  each  case, 
to  produce  the  squint,  but  in  a  different  way.  In  other 
words,  in  each  case  a  weakness  of  the  externus  with  a 
contributory  cause,  —  in  one  case  the  amblyopia,  and  in 
the  other  the  relative  hyperopia.  Will  the  innervation 
theory  or  the  antithesis  of  Bonders  include  both  of  these 
cases  ? 

Therefore  I  believe  in  the  proper  study  of  the  causes 
of  squint  we  rrlust  divide  them  into  two  great  classes,  as 
illustrated  in  the  cases  given  above.  Perhaps  we  may 
not  be  able  to  "  draw  the  line  "  very  perfectly  between 
these  two  classes  in  all  cases,  but  we  can  do  so  near 
enough  for  all  practical  purposes.  As  I  have  watched 
and  studied  my  own  cases  I  feel  almost  positive  we  can 


S  OK  HETEROTROPIA. 


95 


do  so,  while  I  have  verified  my  conclusions  over  and  over 
again  in  my  clinical  work. 

In  May,  1894,  I  read  a  paper  on  Strabismus  before  the 
Medical  Society  of  the  county  of  New  York,  in  which  I 
made  the  proposition  to  separate  the  cases  into  two 
classes,  and  since  then  I  have  satisfied  myself  of  the  cor- 
rectness of  my  proposition  ;  but,  at  the  same  time,  I 
would  still  further  advance  my  ideas  on  the  muscular 
theory.  In  both  classes  of  cases  I  would  also  place 
the  balance  of  power  in  the  ocular  muscles  as  the  true 
and  primal  cause  of  all  cases  of  strabismus,  or  as  Walfors 
would  have  us  believe,  on  "  an  antecedent  anomaly  of  the 
muscles";  and  that  innervation,  or  the  position  of  rest, 
has  nothing  to  do  with  it.  If  I  am  not  mistaken,  this  can 
be  proved  in  all  cases. 

Now  this  balance  of  power  in  the  action  of  the  straight 
muscles  of  the  eye,  or,  as  Duane  has  so  well  classed  it, 
"  the  power  of  duction  as  shown  by  the  prism  test,"  has 
been  proved  long  ago  by  many  observers.  I  would  par- 
ticularly refer  to  the  tests  made  by  my  friend,  Dr.  J.  M. 
Banister,  Surgeon  U.  S.  A.,  in  his  very  careful  examina- 
tion of  one  hundred  soldiers  who  never  had  any  asthe- 
nopic  symptoms  whatever,  and  with  vision  fg,  or  better. 

This  balance  of  power  of  these  muscles  in  their  relation 
to  each  other,  as  shown  by  the  fusion  power  or  guiding 
sensation,  will  even  during  sleep  determine  the  position 
of  the  visual  axes. 

Placing  then  the  muscular  balance  as  the  essential  con- 
dition in  the  causation  of  squint,  we  also  find  other  minor 
causes  that  will  influence  the  position  of  the  visual  axes. 
First,  congenital  amblyopia  in  one  eye  ;  and  second, 
relative  hyperopia,  as  suggested  by  the  first  part  of  Don- 
ders'  antithesis,  or  any  refractive  condition  from  that  of 
emmetropia  to  the  most  complicated  astigmatism. 

I  have  now  the  memoranda  of  some  400  cases  of  latent 


96 


SJ'KAftlSMUS. 


and  fixed  squint,  all  those  in  which  the  examinations  were 
complete  showing  the  same  underlying  'cause.  These 
cases  I  have  divided  as  follows : 

Esophoria  .  ...  45  cases 

Exophoria  .  .  .  .  68      " 

Hyperphoria,  right  or  left  .  .  8      " 

Anaphoria  ....  i  case 

Cases  looking  to  right  or  left        .  .  several 

A  total  of  about  130  cases. 
Convergent  squint,  ist  class          .  .  93  cases 

"  "       2nd  class          .  .  129     " 

Divergent        "         ist  class          .  .  9     " 

"  "        2nd  class          .  .  21     " 

Cases  in  which  the  class  could  not  be  recorded,  23 
This  makes  a  total  of  over  400  cases  that  have  been  examined  by 
myself  and  upon  which  my  present  opinions  are  based. 

On  these  cases  the  following  operations  have  been  per- 
formed : 

Advancements         ....  4  cases 

Shortening  externi  .  .  72      " 

Shortening    interni  .  .  38      " 

Total         .  .  .  .  .114  cases. 

Tenotomy  of  externus       .  .  .          105  cases 

"          "    internus       .  .  94      " 

"  "    inferior         .  .  .  4      " 

"          "    superior        .  .  23      " 

Total        .  .  .  .  .226  cases 

giving  340  operations  on  the  entire  series. 

Now  we  will  note  the  refraction  of  all  these  cases  of 
squint,  as  far  as  the  condition  could  be  determined  by  the 
objective  examination  : 

Convergent  squint,  Hyperopia        .  .  165  cases 

"      Hy.  with  Ah.    .  .  34     " 

"                "      Ah.                     .  .  8     " 

"               "      Myopia              .  .  6     " 

"                "      My.  with  Hy.    .  .  i     " 

"                "      Emmetropia     .  .  4     " 

Refraction  not  recorded      .             .  25     " 

In  all                       .                         .  .  241  cases 


STRABISMUS  OR  HETEROTROPIA.  97 

Divergent  squint,  Hyperopia  .  .  17  cases 

"     Hy.  with  Ah.  .  .  5     " 

"     Ah.  .  .  8     " 

"  "     Myopia    .  .  .  7     " 

"  "     My.  with  Am.  .  .  4     " 

"  "     Emmetropia  .  .  2     " 

Refraction  not  recorded     .  .  .  6     " 

In  all        .  .  .  .  .  49  cases 

The  large  number  of  cases  showing  hyperopia  is  due  to 
the  fact  that  many  of  my  records  are  from  the  clinics  at 
the  Post-Graduate  Hospital  where  the  examinations  were 
not  very  exact,  otherwise  I  think  that  many  of  them  would 
show  hyperopic  astigmatism.  It  is  also  remarkable  to 
note  the  large  number  of  cases  of  divergent  squint  that 
show  hyperopia  and  astigmatism.  As  regards  the  sex  of 
the  cases,  when  recorded  I  found  it  to  be  about  equally 
divided. 

I  will  now  call  attention  to  what  I  consider  determines 
these  two  classes,  why  they  should  be  thus  separated,  and 
the  causes  therein  acting  to  produce  squint.  In  these 
classes  I  feel  positive  we  may  place  all  our  cases  of 
squint,  whether  divergent  or  convergent  —  (those  cases 
with  a  vertical  deviation  need  not  be  considered  in 
classes)  —  and  I  hope  to  show  some  material  advantage  in 
so  separating  them. 

In  those  of  the  first  class  we  find  this  condition  :  Ambly- 
opia,  always  congenital,  vision  less  than  ro°<j,  associated 
with  an  abnormal  balance  of  power  in  the  lateral  moving 
muscles.  Hence  with  the  loss  of  the  fusion  power  or 
the  guiding  sensation  the  eye  quickly  turns  in  the  direc- 
tion of  the  most  powerful  acting  muscle,  namely,  the  inter- 
nus,  in  convergent  squint,  and  the  externus,  in  divergent 
squint,  etc.  This  is  well  illustrated  by  the  early  onset 
of  the  squint  in  cases  of  this  class,  and  it  is  very  clearly 
proved  by  the  cases  of  amblyopia  of  the  same  kind  that 
do  not  squint  and  which  always  show  the  same  power  of 


98 


STRABISMUS. 


abduction  as  adduction,  or  the  same  rotation  in  the  field  of 
version. 

In  the  second  class  of  cases  we  find  this  condition  : 
Some  refractive  error,  either  hyperopia  or  myopia,  with  or 
without  an  astigmatism,  and  the  vision  nearly  the  same 
in  each  eye,  but  seldom  less  than  ?8  in  one  and  better  in 
the  other ;  and  with  this  an  "  antecedent  anomaly  of  the 
muscles  "  or,  in  other  words,  a  weakness  of  some  one  of  the 
straight  muscles  of  the  eye  acting  either  laterally  or  verti- 
cally. In  convergent  squint  there  is  a  deficiency  in  the 
power  of  the  externi,  and  in  divergent  squint  there  is  a 
deficiency  in  the  power  of  the  interni,  while  the  same  rule 
will  apply  to  all  squints  in  the  vertical  direction.  Cases 
of  vertical  squint  are  very  difficult  to  prove  by  any  other 
theory. 

In  the  second  class  of  cases,  if  the  squint  has  existed 
for  any  length  of  time  we  may  have  what  is  called  "  am- 
blyopia  ex  anopsia"  arising  simply  from  non-use  and  the 
suppression  of  the  image  in  the  squinting  eye.  I  think 
these  cases  furnish  the  reports  of  the  restoration  of  the 
vision  after  an  operation,  or  after  the  accidental  loss  of 
vision  in  the  fixing  eye.  (See  article  on  Amblyopia).  The 
theory  as  applied  to  this  class  is  beautifully  illustrated  in 
those  not  infrequent  cases  of  convergent  squint  with  my- 
opia, a  condition  that  I  do  not  think  can  be  explained 
in  any  other  way  than  that  of  a  muscular  anomaly. 

The  fact  that  all  the  various  refractive  conditions  may 
exist  without  squint  has  been  a  very  difficult  problem  to 
explain,  or  rather  I  have  not  been  satisfied  with  the 
explanations  that  have  been  offered,  so  far  as  I  have  been 
able  to  consult  the  writers  on  this  subject.  Yet  it  is 
partly  from  this  fact  that  I  have  come  to  my  own  conclu- 
sions, and  I  have  yet  to  see  and  study  the^case  that  can 
not  be  clearly  placed  in  one  of  these  two  classes 
and  which  will  show  an  imbalance  of  the  ocular  muscles. 


STRABISMUS  OR  HETEROTROPIA, 


99 


Fuchs,  in  the  last  edition  of  his  text-book,  gives  the 
etiology  of  strabismus  as  follows:  "Strabismus  is,  there- 
fore, the  result  of  the  combined  action  of  two  factors, 
diminution  in  the  visual  power  of  one  of  the  eyes  and  a 
pre-existing  disturbance  of  the  muscular  equilibrium, 
according  as  the  latter  factor  consists  in  a  preponderance 
of  the  external  or  internal  ocular  muscles,  a  convergent 

O 

or  a  divergent  squint  is  produced,"  yet  he  considers  all 
the  cases  of  divergent  squint  as  being  myopic. 

As  it  is  utterly  impossible  to  place  them  all  under  one 
general  head,  I  would  separate  them  into  these  two 
classes  so  that  my  theory  will  cover  all  cases,  and  in  both 
classes  we  will  find  a  certain  weakness  or  want  of  power 
in  one  of  the  straight  muscles  of  the  eye. 

Let  me  now  resume  the  argument  in  reference  to  the 
first  class,  which  I  will  illustrate  with  a  typical  case  :  A 
child,  born  of  perfectly  healthy  parents,  is  normal  in  all 
respects  —  the  visual  axes  are  perfectly  parallel,  but  the 
power  of  the  external  muscles  of  the  eyes  is  not  properly 
balanced.  Now  one  eye  is  amblyopic,  in  which  there  is 
weak  fusion  power  and  partial  absence  of  the  guiding 
sensation  in  that  eye,  hence  there  is  no  tendency  to  fix 
the  visual  line  (and  I  believe  this  power  comes  very  early 
in  life)  ;  then,  with  these  conditions,  it  seems  reasonable 
to  claim  that  the  eye  will  turn  in  the  direction  of  the 
most  powerful  muscles.  In  convergent  squint  the  eye 
turns  inward  and  remains  so,  as  there  is  no  stimulation 
to  make  it  resume  its  normal  position.  The  same  ar- 
gument may  apply  to  divergent  squint  under  the  same 
conditions. 

Before  proceeding  further  we  must  understand  what 
this  condition  of  amblyopia  is  :  objectively  we  can  find 
no  evidence  of  a  want  of  vision,  for  the  examination  with 
the  ophthalmoscope  gives  us  the  same  picture  as  is  shown 
in  the  other  eye,  and  as  Maddox  says,  the  macula  appears 


100  STRABISMUS. 

"  tantalizingly  perfect "  ;  but  subjectively  there  is  all  the 
evidence  of  the  want  of  vision.  These  amblyopic  eyes 
will  not  have  a  restoration  of  the  vision  under  other  con- 
ditions, no  matter  what  may  be  the  testimony  to  that 
effect  by  other  writers.  I  make  this  statement  because  I 
have  failed  to  ever  meet  a  case ;  because  a  careful  study 
of  the  various  reports  shows  some  flaws  in  the  estimation 
of  the  visual  power ;  and  because  other  observers,  just  as 
careful  and  experienced,  have  made  the  same  statement. 
Hence  does  not  our  clinical  experience  teach  us  that  we 
do  have  a  congenital  amblyopia,  not  a  suppression  of  the 
retinal  images  ?  For,  just  as  soon  as  we  can  possibly  test 
the  vision  of  a  child  who  squints,  say  at  five  years  of  age, 
we  find  it  less  than  ^  ;  and  waiting  five  years  longer  it  is 
still  the  same.  Can  any  one  claim  that  there  has  been  a 
loss  of  the  physiological  sensibility  of  the  retina  to  reduce 
the  vision  from  normal  to  less  than  {&,  in  the  first  five 
years  of  life,  and  yet  after  that,  or  in  the  next  five  years, 
with  the  squint  remaining,  there  has  been  no  further  loss 
of  retinal  sensibility  and  the  vision  remains  the  same  ? 
I  would  also  refer  to  those  cases  where  we  have  an  am- 
blyopia of  the  same  kind,  in  which  there  never  has  been 
any  tendency  to  squint  and  yet  the  vision  remains  the 
same  through  life.  They  seem  to  have  binocular  fixation, 
but  careful  examination  will  show  no  preponderance  in 
power  of  any  muscle.  I  therefore  cannot  understand  the 
claim  that  this  condition  is  amblyopia  ex  anopsia. 

May  we  not  forcibly  ask  :  "  Does  all  the  loss  of  vision 
take  place  in  the  first  five  years  of  life  and  then  remain 
so?"  To  me"  a  negative  answer  is  hardly  required  to 
such  a  self-evident  fact. 

Furthermore,  if  in  the  same  cases  the  squint  never  is 
corrected  it  may  remain  until  they  are  about  thirty  years 
of  age  and  then  the  convergence  disappears,  the  visual 
axes  are  parallel  and  remain  so,  yet  we  find  the  vision 


STRABISMUS  OK  HETEROTROPIA  IOI 

about  the  same  as  stated  above.  This  is  the  so-called 
natural  cure  of  squint.  It  is  very  rare,  and  only  confirms 
the  muscular  condition  as  the  essential  cause. 

Moreover,  examine  those  cases  of  monocular  amblyo- 
pia  who  never  had  any  deviation  of  the  visual  lines,  and 
invariably  you  will  find  that  the  normal  balance  of  power 
does  not  exist  —  that  adduction  is  the  same  as  abduction, 
that  version  of  the  eyes  is  normal,  that  there  is  no  pre- 
ponderance of  power  in  either  of  the  lateral  muscles,  and 
that  the  amblyopic  eye  simply  follows  its  fellow  in  the 
associated  movements.  (See  Amblyopia  and  the  Resto- 
ration of  Vision). 

To  repeat :  What  then  are  the  conditions  of  our  two 
classes  of  cases  ? 

First,  congenital  amblyopia  associated  with  an  abnormal 
balance  in  adduction  and  abduction  ;  taking  from  the  eye 
its  power  of  fusion  or  the  guiding  sensation,  the  eye  must 
turn  in  the  direction  of  the  most  powerful  muscles  — 
namely,  inward  or  outward,  up  or  down,  as  the  case  may 
be  —  the  same  conditions  acting  on  the  other  eye  under 
the  screen  test,  for  the  visual  lines  maintain  their  respec- 
tive distances,  showing  that  the  squint  is  concomitant  or 
functional. 

There  must  be  a  pre-existing  disturbance  of  the  muscu- 
lar equilibrium  in  squint  \vhich  can  not  be  due  to  the  eye 
assuming  a  position  of  rest,  nor  to  the  innervation,  and, 
when  the  retina  is  deprived  of  its  guiding  sensation  by  the 
amblyopia,  the  eye  must  turn  in  the  direction  of  the  most 
powerful  muscle.  The  above  argument  will  apply  to  diver- 
gent and  vertical  squint,  as  in  all  these  cases  we 
have  a  muscular  anomaly  acting  in  the  same  way. 

Second,  in  this  class  a  child  is  born  with  perfectly  nor- 
mal vision  in  each  eye.  There  is  generally  an  error  of 
refraction,  either  with  or  without  astigmatism,  and  there 
is  always  an  imbalance  of  the  ocular  muscles. 


102 


STRABISMUS. 


Now  we  notice,  as  the  child  plays  with  small  toys  or  uses 
the  eyes  at  a  near  point,  that  it  begins  to  turn  one  eye 
inward  at  times  —  called  periodic  squint.  This  condition 
may  continue  until  the  child  is  five  years  old,  when  one 
eye  constantly  turns  inward  —  called  foxed  squint.  Does 
hyperopia  cause  this,  when  we  see  so  many  hyperopes 
that  have  no  tendency  to  squint  ?  May  we  not  reason- 
ably attribute  it  to  an  insufficiency  of  the  externif  I 
think  so,  and  this  imbalance  of  the  ocular  muscles  will 
explain  the  reasons  for  squint  in  cases  of  emmetropia, 
myopia,  or  astigmatism  without  hyperopia. 

Now  strabismus  is  generally  convergent  and  the  refrac- 
tion hyperopic  ;  why  ?  First,  because  hyperopic  refrac- 
tion is  the  most  common  condition  and  second,  because 
the  centers  for  convergence  and  accommodation  are  very 
closely  associated  in  the  oculo-motor  tract  beneath  the 
aqueduct  of  Sylvius  and  the  floor  of  the  fourth  ventricle. 
Now  as  the  child  begins  to  use  the  eyes,  if  it  is  hyperopic 
it  requires  a  greater  power  of  accommodation.  The  cor- 
rection of  the  hyperopia,  by  the  increased  accommodation, 
causes  a  stimulation  of  the  power  of  convergence ;  then 
with  an  existing  want  of  power  in  the  externi  we  have  the 
convergence  of  the  visual  lines. 

Assuming  this  to  be  the  condition,  what  becomes  of  the 
image  formed  on  the  retina  of  the  squinting  eye  ?  First, 
the  image  of  the  object  falls  upon  the  least  sensitive  part 
of  the  retina — namely,  the  inner  peripheral  part  —  there 
forming  an  indistinct  image  ;  second,  the  image,  what- 
ever it  may  be,  that  is  formed  at  the  macula,  or  most  sen- 
sitive part  of  the  retina,  is  not  in  focus,  the  rays  coming 
from  a  far  different  plane  than  the  object,  and  again  we 
have  an  indistinct  image.  Consequently  the  visual 
centers  will  readily  suppress  these  indistinct  images 
formed  on  the  retina,  and  only  single  vision  results.  We 
can  now  say  there  is  a  loss  of  vision  from  "  physiological 


STRABISMUS  OR  HETEROTROPIA. 


103 


sensibility  through  psychical  exclusion  in  the  squinting 
eye,"  but  we  must  remember  that  the  sensitive  retinal 
elements  are  still  the  same  and  may  be  developed  to  their 
former  power  when  the  eye  is  used  under  proper  condi- 
tions. The  vision  is  naturally  reduced  in  one  eye  from 
disuse,  the  so-called  amblyopia  ex  anopsia,  and  may  be 
improved  by  an  operation,  by  glasses,  or  by  the  exclusion 
of  the  other  eye. 

Strabismus  has  been  divided  into  latent,  alternating, 
and  fixed,  each  and  severally  one  of  degree,  and  if  so  do 
they  not  all  depend  upon  the  relative  power  of  the 
straight  muscles  of  the  eyes  ?  It  has  been  said  that  I 
"fall  into  error  when  speaking  of  the  strength  of  the 
individual  muscles  estimated  in  this  manner,"  referring  to 
the  test  with  prisms,  and  that  "  his  argument  seems  illogi- 
cal "  ;  but  if  I  am  in  "  error,"  or  "  illogical,"  I  shall  be  glad 
to  be  convinced  of  my  fault.  I  have  studied  the  cases  of 
squint  coming  under  my  observation  time  and  time  again, 
both  in  my  private  and  hospital  practice,  and  have  read 
all  the  literature  that  I  can  find  on  this  subject,  and  I 
have  only  become  more  and  more  convinced  that  this 
theory  of  the  action  and  the  relative  power  of  the  ocular 
muscles  is  the  chief  and  determining  cause  of  all  cases  of 
strabismus.  I  have  yet  to  meet  with  a  case  that  cannot 
be  explained  in  one  of  these  two  classes,  and  in  which  I 
cannot  readily  demonstrate  the  influence  of  the  ocular 
muscles  in  the  production  of  the  squint. 

Moreover,  we  meet  so  many  cases  with  all  the  other 
essential  conditions  that  we  find  in  squint,  and  yet  there  is 
no  deviation  of  the  visual  lines.  Take,  for  instance,  those 
cases  of  amblyopia  congenitalis  in  one  eye,  perhaps 
hyperopic  or  astigmatic  ;  no  asthenopia  ;  intelligent,  bright 
people  between  fifteen  and  thirty  years  of  age  ;  they  have 
perfect  binocular  fixation,  but  no  binocular  vision  or 
sense  of  the  "  third  dimension,"  they  have  never  had  the 


IO4 


STRABISMUS. 


slightest  tendency  to  squint,  yet  the  amblyopic  eye  follows 
the  other  in  all  parts  of  the  field  of  fixation.  I  have 
tested  these  cases  over  and  over  again,  and  have  invariably 
found  a  tendency  to  exophoria,  or  in  other  words,  by  the 
test  in  which  I  am  said  to  be  in  error,  the  relative  power 
of  the  externi  was  the  same  as  that  of  the  interni,  if  not 
slightly  greater.  Abduction  was  the  same  as  adduction, 
and  with  the  absence  of  the  fusion  power  there  was  no 
tendency  to  turn  the  amblyopic  eye  imvard. 

Furthermore,  I  have  never  seen  an  explanation  of  the 
cause  of  squint  in  myopia  when  it  is  convergent.  Surely 
"  the  position  of  rest"  cannot  cause  it,  nor  the  last  clause 
of  Donders'  antithesis ;  but,  on  the  other  hand,  a  decided 
weakness  of  the  externi  may  readily  cause  the  eye  to  turn 
in  under  the  stimulation  for  fixation  at  the  near  point. 

Again,  if  the  innervation,  the  position  of  rest,  the  hyper- 
opia,  or  any  other  of  the  theories  advanced  is  the  cause 
of  the  strabismus,  then  why  do  we  operate  on  the  muscles 
by  tenotomy  or  advancements  that  simply  and  only  alter 
the  relative  power  of  the  straight  muscles  of  the  eyes  ? 
Edward  Jackson  well  says  :  "  How  will  an  operation  influ- 
ence the  innervation  of  the  muscles  acting  on  the  eyeball, 
or  will  it  leave  the  innervation  quite  unaltered?"  Does 
not  this  muscular  theory  apply  forcibly  to  the  action  of 
the  muscles  in  the  vertical  meridian,  in  which  we  have  an 
upward  or  a  downward  strabismus  ? 

Maddox  says,  "  Non-paralytic  squint,  therefore  con- 
comitant, is  purely  due  to  excessive  activity  of  the  con- 
verging innervation,"  but  I  do  not  think  his  arguments 
prove  it,  as  sq'uint  does  not  always  disappear  under  the 
influence  of  an  anesthetic,  and  "innervational  habit "  has 
nothing  to  do  with  physiological  conditions. 

I  would  also  refer  to  the  "  natural  cure  of  squint,"  in 
which  you  will  have  the  history  of  convergence  of  one  of 
the  eyes  for  several  years,  until  they  have  become  about 


STRABISMUS  OR  HETEROTROPIA. 


105 


thirty  years  old,  when  the  squint  disappears  and  they  have 
perfect  binocular  fixation.  This,  as  far  as  my  observation 
goes,  always  occurs  in  the  squint  of  the  first  class,  or  those 
with  congenital  amblyopia.  Now  examine  these  cases 
and  you  will  find  the  amblyopia  the  same  in  reference  to 
the  vision,  but  if  you  carefully  test  the  relative  power  of 
the  lateral  moving  muscles  by  the  prism  test  you  will  have 
abduction  the  same  as  adduction.  Now  what  has  become 
of  the  "  innervation"  or  the  "habit"?  Has  not  the  con- 
tracted internus  lost  its  power  after  all  these  years  and  the 
eye  found  its  natural  position  and  follows  the  other  ? 

I  do  not  wish  to  present  many  illustrative  cases  nor 
many  arguments  in  favor  of  this  muscular  theory,  but  I 
shall  be  pleased  to  see  the  case  of  squint  of  any  kind  that 
cannot  be  explained  under  the  head  of  one  of  the  two 
classes  (always  excepting  any  case  of  paretic  squint),  with 
an  essential  weakness  of  one  or  more  of  the  muscles. 

Finally,  with  these  conclusions  in  reference  to  the  the- 
ory of  strabismus,  granting  that  they  are  correct,  the 
management  of  all  our  cases  is  clearly  indicated,  having 
determined  the  class  to  which  the  case  may  belong.  It 
only  requires  the  intelligent  application  of  the  treatment 
to  end  in  success. 

As  many  children  are  brought  to  us  too  young  to  be 
tested  in  reference  to  the  visual  powers,  either  by  the  use 
of  the  test-type  or  glasses,  Worth  has  suggested  a  simple 
method  that  may  give  some  very  useful  information  as  to 
the  visual  acuity.  If  the  child  is  too  young  to  know  the 
letters  or  to  count  the  fingers,  Worth  covers  one  eye  with 
a  bandage  and  then  taking  different  sizes  of  white  marbles 
or  ivory  balls  —  say  from  one-half  inch  in  diameter  to  two 
inches  —  he  rolls  them  on  the  floor  away  from  the  little 
patient,  and  after  the  marbles  have  passed  about  twenty 
feet  the  child  is  permitted  to  run  after  them.  In  this 
way,  by  the  ability  to  find  the  marbles  and  the  direction 


IO6  STRABISMUS. 

the  child  will  run  we  can  easily  judge  the  visual  acuity 
and  record  it  in  the  usual  way.  It  will  be  best  to  test  the 
fixing  eye  first. 

Now  what  are  the  indications  of  the  first  class,  or  stra- 
bismus with  congenital  amblyopia?  I  do  not  believe  that 
in  any  case  or  in  any  way  we  can  restore  binocular  vision  ; 
but  our  aim  must  simply  be  to  equalize  the  muscular  bal- 
ance and  so  attain  a  perfect  cosmetic  effect  in  order  that 
the  eye  may  keep  its  natural  position  with  reference  to  the 
fixing  eye.  After  an  operation  glasses  may  be  ordered 
and  used,  if  there  are  any  indicatious  for  them,  but  all 
attempts  to  restore  the  vision  will  be  useless. 

Our  treatment  then  becomes  simply  one  of  an  operation 
to  improve  the  cosmetic  appearance,  and  that  by  one 
operation  only,  as  shortening  of  the  weak  muscle  and  a 
complete  tenotomy  of  the  powerful  one.  If  we  put  a 
"tuck"  in  the  weak  muscle,  externus  or  internus,  as  the 
case  may  be,  with  the  catgut  suture,  then  do  a  complete 
tenotomy  on  the  opposing  muscle,  and  tie  our  suture  so  as 
to  bring  the  eye  into  the  primary  position  we  will  have 
corrected  an  ocular  defect  permanently,  with  a  single 
operation.  I  have  followed  this  procedure  in  my  office 
and  clinic  for  several  years  and  have  yet  to  record  the 
first  failure. 

In  this  class  and  by  this  method  we  will  not  have 
to  operate  on  the  fixing  eye  —  a  great  comfort  to  our 
patients  —  while  the  suture  will  be  absorbed,  so  that  we 
do  not  require  a  second  operation  for  its  removal. 

These  cases  cannot  be  cured  by  the  use  of  atropine  and 
glasses,  but  must  have  an  operation  just  as  soon  as  the 
visual  power  can  be  tested,  so  that  we  may  decide  if  one 
eye  is  amblyopic,  and  after  that,  order  glasses  if  needed. 
Amblyopia  is  usually  associated  with  hyperopia,  but  I  do 
not  think  that  the  refractive  condition  is  an  essential 
factor  in  the  causation  of  this  class  of  strabismus. 


STRABISMUS  OR  HETEROTROPIA.  \QJ 

In  the  treatment  and  technique  of  our  second  class  of 
cases  —  and  these  are  in  the  majority  —  we  are  now  con- 
fronted with  a  far  different  problem,  in  which  we  must 
seek  to  restore  binocular  vision,  perfect  fixation,  and  the 
ultimate  restoration  of  the  vision  in  an  eye  that  has 
from  disuse  partly  lost  its  power  to  see. 

Now  we  have  two  conditions  to  consider  —  primarily, 
an  imbalance  of  the  ocular  muscles  ;  and  secondarily,  a 
refractive  error.  These  two  conditions  must  be  worked 
out  with  all  the  objective  and  subjective  tests  at  our  com- 
mand before  we  take  into  consideration  any  operative 
interference.  Here  we  may  have  all  kinds  of  refractive 
conditions  and  all  the  different  degrees  of  squint,  not 
latent,  but  alternate,  periodic,  or  fixed,  from  that  of  the 
slightest  diplopia  to  a  fixed  squint,  in  which  there  is  mon- 
ocular vision  with  the  fixing  eye  and  generally  reduced 
vision,  with,  perhaps,  an  eccentric  fixation  area  in  the 
other  eye. 

Hence,  the  exact  and  correct  estimation  of  the  refrac- 
tion, even  under  the  full  effect  of  a  mydriatic,  is  the  first 
essential,  as  while  I  believe  all  these  cases  are  associated 
with  an  imbalance  of  the  ocular  muscles,  either  those  act- 
ing laterally  or  those  acting  vertically,  the  correction  of 
the  refractive  error  will  in  many  cases  so  relieve  the  strain 
on  the  fixation  power  and  restore  the  giiiding  sensation 
that  the  use  of  proper  glasses  will  correct  the  tendency  to 
a  malposition  of  the  visual  lines  and  the  squint  disappear. 
Some  writers  claim  twenty-five  to  thirty  per  cent,  correc- 
tion by  glasses.  My  results  fall  far  below  this,  possibly 
ten  per  cent.  But  this  procedure  will  not  succeed  in  all 
cases  of  the  second  class,  and  after  the  glasses  have  been 
adjusted  the  squint  sometimes  remains.  We  must  then 
decide  on  an  operation  and  look  for  our  indications  in 
the  power  of  the  opposing  muscles. 

Upward  or  downward  squint  will,  as  a  rule,  only  require 


IO8  STRABISMUS. 

a  complete  tenotomy  on  the  most  powerful  muscle  unless 
there  is  a  decided  weakness  shown,  when  a  shortening 
would  be  indicated  ;  while  in  the  lateral  squints,  particu- 
larly those  of  slight  degree,  we  should  first  advance  or 
shorten  the  weaker  muscle  or  muscles,  if  indicated,  and 
if  the  power  of  rotation  inward  is  still  too  great  in  the 
field  of  fixation,  we  may  safely  do  a  complete  tenotomy. 

All  cases  of  this  second  class  must  be  carefully  studied 
according  to  their  degree  and  indications,  but  in  all  the 
correction  of  the  refraction  vf\.\\^>\.  follow  the  operation. 

In  the  first  class  I  do  not  think  that  the  educational 
treatment  will  be  of  any  service,  but  in  the  second  class 
the  education  of  the  squinting  eye  to  fix  and  appreciate 
'  the  images  will  be  of  great  service,  and  I  might  say  that 
the  object  of  this  work  is  to  prove  that  in  the  first  class  of 
cases  it  is  useless  to  resort  to  any  measures  except  oper- 
ation, and  in  those  of  the  second  class  we  must  resort  to 
all  reasonable  measures,  before  deciding  to  operate.  I 
have  tried  to  show  the  indications  for  each  procedure. 

I  do  not  think  that  special  tables  of  all  the  cases  of 
squint  —  both  convergent  and  divergent  —  that  I  have 
records  of  will  be  of  much  service,  but  a  resume  of  the 
cases  before  mentioned  may  be  helpful.  The  onset  shows 
that  they  may  occur  at  any  age,  from  that  of  the  first 
week  in  life  (two  cases),  to  that  of  twenty-eight  years  (one 
case).  Dividing  them  into  classes  I  have  notes  of 

First  class,  $?$  or  less  in  the  squinting  eye  —  86, 

Second  class,  f  §  or  better  in  the  squinting  eye  —  106,  and 
37  visjon  not  recorded. 

Glasses  ordered  in  48  cases,  all  second  class,  with  correc- 
tion of  the  squint  in  16  cases  —  about  ten  per  cent. 

Five  cases  gave  a  history  of  operation  before  they  were 
seen  by  me,  with  failure  of  result. 

Operations.  All  cases  operated  upon  in  the  office 
showed  an  excellent  final  result  in  cosmetic  appearance, 


STRABISMUS  OR  HETEROTROPIA. 


ICX) 


but  very  few  had  binocular  vision  ;  while  I  have  failed  to 
find  any  material  improvement  in  the  vision  of  the  cases 
which  seem  to  have  congenital  amblyopia.  The  operation 
performed  in  my  earlier  cases  was  simple  tenotomy  - 
single  or  double  —  of  which  I  note  thirty-five  with  good 
final  results,  divergence  following  after  some  years,  in 
two  cases. 

The  operation  for  shortening  with  the  catgut  suture 
was  performed  sixty  times,  in  all  of  which  I  had  a  good 
result,  though  many  of  them  also  had  a  tenotomy  at  the 
same  time.  I  have  had  few,  if  any,  accidents  with  my 
operations,  in  one  case  a  small  artery  was  cut,  with  free 
bleeding  behind  the  eyeball,  causing  a  slight  exophthal- 
mos.  This  was  readily  absorbed  under  a  pressure  band- 
age. In  another  an  hsemophilic  (I  did  not  know  of  this 
beforehand),  after  shortening  the  internus  I  had  bleeding 
from  the  wound,  quite  serious,  for  ten  days.  The  con- 
stant efforts  to  stop  the  hemorrhage  seemed  to  destroy 
the  effects  of  the  operation  and  the  result  was  a  failure 
to  correct  the  divergence. 

Fourteen  cases  are  recorded  as  having  been  examined 
by  the  tropometer  and  all  of  these  showed  weakness  of 
the  externi  in  convergent  squint,  and  of  the  interni  in 
divergent  squint,  with  decided  improvement  in  the  rota- 
tion of  the  eyes  in  the  field  of  version  after  the  operation. 

Finally,  I  now  consider  that  the  best  operation  for  the 
correction  of  squint  is  that  of  shortening  both  of  the 
weak  muscles  in  the  second  class,  and  then  a  careful 
tenotomy  if  needed  ;  while  in  the  first  class  a  shortening 
of  the  weak  muscle  and  tenotomy  of  the  opponent  on 
the  amblyopic  eye  will  be  all  that  is  necessary  in  the  vast 
majority  of  cases. 

Apparent  Squint.  A  few  words  as  to  this  condition 
will  be  necessary  for  the  sake  of  completeness.  As  the 
term  implies,  this  is  not  a  true  squint ;  in  other  words 


HO  STRABISMUS. 

there  is  no  deviation  or  tendency  to  deviation  of  the  vis- 
ual lines  but  simply  an  apparent  deviation  of  the  optic 
axes  with  true  fixation  of  the  visual  lines,  and  true  binoc- 
ular vision.  This  statement  may  seem  somewhat  para- 
doxical, but  we  must  consider  that  we  do  not  judge  the 
position  of  the  eyes  by  the  visual  lines,  which  we  can  not 
see  but  by  the  position  of  the  optic  axes,  or,  in  better 
words,  by  the  position  of  the  center  of  the  pupillary 
space.  Now  it  has  been  well  proven,  by  careful 
scientific  examination,  that  the  visual  lines  and  the 
optic  axes  do  not  coincide  but  form  a  certain  angle, 
the  apex  of  which  is  really  at  the  rotational  point 
of  the  eye,  but  for  all  practical  purposes  we  may  con- 
sider that  these  lines  will  cross  at  the  nodal  point  of 
the  eye,  situated  at  the  posterior  part  of  the  lens.  We 
have  then  two  axes  to  consider  in  this  subject :  First,  the 
visual  line,  drawn  from  the  center  of  the  object  looked  at, 
through  the  nodal  point  to  the  center  of  the  macular 
region  or  yellow  spot.  This  line  fixes  the  vision  on  the 
object.  Second,  we  have  the  optic  axis,  passing  through 
the  nodal  point  from  the  anterior  to  the  posterior  pole  of 
the  eye.  These  lines  wil|  form  an  angle  at  the  nodal 
point,  and  this  has  been  called  the  angle  "alpha,"  or  angle 
"a,"  and  should  be  remembered  in  contradistinction  to 
the  visual  angle.  Landolt  has  designated  this  angle  "  a  " 
as  the  angle  "  Kappa,"  for  a  full  description  of  which  I 
would  refer  the  reader  to  his  classical  work  on  this  sub- 
ject. Now  we  find  that  in  an  examination  this  angle  may 
be  neutral,  that  is,  the  two  axes  will  coincide  or  it  may  be 
phis  or  positive ,  when  the  optic  axis  passes  to  the  outer 
or  temporal  side  of  the  visual  line,  showing  divergence,  or 
it  may  be  minus  or  negative,  when  the  optic  axis  passes  to 
the  inner  or  nasal  side  of  the  visual  line,  showing  an 
apparent  convergence.  From  this  it  will  be  seen  that 
according  to  the  extent  or  size  of  this  angle  "a"  we  may 


STRABISMUS  OR  HETEROTROPIA.  In 

have  an  apparent  deviation,  judging  from  the  position  of 
the  pupillary  space,  while  there  is  present  true  fixation  and 
no  deviation  of  the  visual  lines. 

Diagnosis.  I  give  the  method  of  Landolt  for  the 
measurement  of  this  angle,  from  N orris  and  Oliver's 
System,  Vol.  iv,  p.  46  :  "  The  affected  eye  being  placed 
in  the  center  of  the  perimeter,  we  cover  the  sound  eye 
and  have  the  patient  fix  the  flame  at  the  summit  of  the 
arc.  In  this  case  the  visual  line  is  directed  toward  the 
zero  point  o.  If  the  visual  line  coincides  with  the  pupil- 
lary axis  the  reflex  of  the  flame  would  appear  to  be  at 
the  center  of  the  pupil  when  we  look  at  the  observed 
eye  from  the  summit  of  the  arc.  To  find  at  once  the 
direction  and  the  degree  of  the  angle  we  leave  the  flame 
immobile  at  the  zero  point  and  we  move  our  eye  along 
the  arc  until  we  have  found  the  point  at  which  it  is  neces- 
sary to  view  the  observed  eye  in  order  that  the  reflex  of 
the  flame  may  appear  at  the  center  of  the  pupil.  The 
corresponding  degree  on  the  arc  then  represents  twice 
the  angle."  We  can  readily  understand  from  this  that 
the  angle  of  incidence  being  equal  to  the  angle  of  re- 
flection the  line  of  the  optic  axis  must  be  on  the  arc,  mid- 
way between  the  zero  point  and  the  degree  on  the  arc. 

Landolt  adds  :  "  It  might  seem  that  it  would  be  simpler 
to  have  the  patient  fix  the  zero  point  of  the  arc,  and  carry 
the  candle  along  the  arc,  in  order  to  find  at  A.  directly,  this 
angle,"  and  this  method  may  be  used  in  estimating  small 
degrees  of  actual  squint  but  the  angle  "a"  is  very  small 
and  we  can  estimate  it  much  more  readily  by  the  first 
method.  Hartridge  states  that  the  normal  angle  is  about 
5°,  and  Donders  gives  the  angle  in  hyperopiaas  about  8°, 
and  in  myopia  about  2°,  but  it  is  generally  much  less 
than  this,  except  in  cases  where  we  have  an  apparent 
squint,  when,  of  course,  it  is  much  larger.  Maddox  recom- 
mends the  examination  of  the  position  of  the  optic  axis 


112 


STRABISMUS. 


by  the  reflex  from  both  cornea  when  illuminated  by  the 
ophthalmoscopic  mirror.  In  this  case  the  small  images 
will  be  symetrically  placed  on  the  inner  side  of  the  cornea 
and  if  markedly  misplaced  will  show  real  squint.  This 
test  may  be  useful  in  babies  as  a  test  for  a  very  slight 
deviation.  He  further  says,  "  The  angle  alpha  is  due  to 
the  fact  that  the  fovea  centralis  does  not  lie  exactly  at  the 
posterior  pole  of  the  eye,  but  is  slightly  below  and  to  the 


DIAGRAM   SHOWING  THE    ESTIMATION   OF   ANGLE  "A." 

outer  side,  so  that  the  visual  line  must  cross  the  nodal 
point  on  the  inner  side  of  the  anterior  pole  and  when  the 
eye  is  fixed  and  the  image  reflected  from  the  cornea  these 
images  should  lie  to  the  inner  side  of  the  pupillary  space. 
From  this  it  is  evident  that  a  large  angle  "a  "  may  dimin- 
ish a  convergent  squint  in  hyperopia  and  a  divergent 
squint  in  myopia,  but  these  quantities  are  too  small  to  be 
considered  in  real  squint.  "  This  will  be  proved  by  the 
other  test  for  the  actual  deviation,  consequently  this 
examination  for  apparent  squint  becomes  useful  when  we 


STRABISMUS  OK  HETEROTROFIA. 


seem  to  have  a  deviation  of  the  visual  lines  and  yet,  evi- 
dently, have  perfect  fixation.  It  goes  without  saying  that 
no  operation  for  this  condition  should  be  considered.  I 
have  seen  these  cases  and  the  examination  was  very  inter- 
esting, but  they  do  not  cause  any  asthenopic  symptoms, 
and  the  slight  defect  in  the  cosmetic  appearance  of  the 
case  may  be  dismissed.  Landolt  claims  that  this  condi- 
tion should  be  considered  in  the  treatment  of  true  squint, 
but  I  have  never  found  it  necessary,  and  its  influence  is 
so  slight  in  the  cosmetic  effect  and  not  at  all  in  the  ulti- 
mate result  that  I  have  not  suggested  it  in  the  treatment 
of  the  condition  of  heterophoria  or  that  of  heterotropia. 

Amblyopia  and  the  Restoration  of  Vision.  As  I  read  a 
recent  article  by  Dr.  A.  E.  Davis,  in  the  Post-Graduate, 
March,  1900,  on  "  Non-operative  Treatment  of  Strabis- 
mus," in  which  he  speaks,  incidentally,  of  amblyopia, 
these  words  of  Dr.  Drew  occurred  to  me  :  "  A  well-known 
author  has  declared  that  even  the  axioms  of  geometry 
would  be  disputed  if  men's  passions  were  concerned  with 
them,  and  so  it  seems."  From  Dr.  Davis'  article  one 
would  judge  that  there  was  no  true  congenital  amblyopia. 
While  the  writer  endeavors  to  convince  us  that  ambly- 
opia does  not  exist  per  se,  and  argues  against  it,  at  the 
same  time  he  admits  that  it  does  exist  in  certain  cases. 
To  use  his  own  argument, — "  One  case  of  this  kind 
being  more  convincing  than  all  the  negative  evidence 
against  it," —  so  if  the  writer  has  met  with  one  case,  as 
his  paper  clearly  indicates,  then  what  becomes  of  all  his 
arguments  ? 

Again,  I  will  quote  from  the  same  paper :  "  If  this 
amblyopia  is  congenital,  that  is,  organic,  the  educative  or 
non-operative  treatment  of  strabismus  will  be  of  but 
little  benefit,  indeed  ;  but,  if  acquired,  that  is,  functional, 
then  its  possibilities  are  wide  and  the  outcome  hopeful." 
A  postulate  that  I  have  advocated  for  several  years, 


I  !4  STRABISMUS, 

particularly  in  my  last  paper  on  "  The  Theory  of  Squint,"  f 
and  also  in  one  on  "  Crossed  Eyes,"  read  before  the 
County  Medical  Society,  May  28,  1894.  Now,  in  the 
above  proposition  just  quoted,  the  writer  acknowledges 
the  possible  existence  of  congenital  amblyopia,  and  in  the 
next  paragraph  of  his  article  proceeds  to  argue  that  this 
condition  does  not  exist  in  squint  of  any  variety.  But  if 
congenital  amblyopia  does  not  exist  frequently,  will  some 
one  explain  to  me, —  Why  do  we  see  many  cases  of  am- 
blyopia in  one  eye  that  never  had  strabismus,  yet  pre- 
senting all  the  objective  and  subjective  evidence  of  it  ? 

Schweigger  considers  this  congenital  amblyopia,  and 
all  opthalmologists  must  have  met  with  these  cases.  I 
have  seen  many  of  them  in  very  intelligent  people,  in 
which  the  vision  in  one  eye  is  found  to  be  22o°<j  or  less, 
who  state  that  the  vision  has  always  been  the  same  in 
that  eye,  as  they  have  been  tested,  and  worn  glasses  for 
many  years.  They  seem  to  have  perfect  binocular  fixa- 
tion, yet  the  vision  has  always  been  sadly  deficient  in  the 
one  eye.  However,  there  is  no  squint  or  family  history 
to  that  effect,  nor  is  there  any  objective  evidence  with  the 
ophthalmoscope  that  one  eye  is  not  as  good  as  the  other 
eye,  while  both  are  generally  found  to  be  hyperopic  of 
the  same  degree.  Certainly  this  is  pretty  positive  evi- 
dence of  congenital  amblyopia. 

Then,  if  we  acknowledge  that  congenital  amblyopia 
does  exist  more  or  less,  of  what  use  will  the  educative 
treatment  be  ?  Is  it  not  a  waste  of  time  and  want  of 
proper  appreciation  of  the  nature  and  the  causes  of 
squint  ?  Furthermore,  of  what  use  will  our  glasses  and 
other  means  be  in  the  cure  or  correction  of  squint? 

All  these  questions  come  rapidly  to  mind  as  one  con- 
siders the  probable  and  possible  cure  of  squint,  and  at 


The  Ophthalmic  Record,  September,  1899. 


STRABISMUS  OR  HETEROTROPIA. 


once  bring  to  the  physician's  mind  the  question, —  when 
the  case  is  brought  to  him  for  examination  and  opin- 
ion,—  Shall  I  operate  or  not  ? 

My  writings  on  this  point  have  been  plain  and  explicit, 
as  I  have  divided  my  cases  into  the  two  classes :  First, 
if  amblyopia  is  present,  operate  at  once,  as  all  our  educa- 
tive treatment  will  do  no  good  ;  on  the  other  hand,  if 
we  have  only  amblyopia  ex  anopsia,  then  we  will  be 
fully  justified  in  using  all  possible  means  to  effect  a 
cure  before  we  proceed  to  change  the  balance  of  the  mus- 
cular power  by  an  operation. 

In  Gould's  Year  Book  we  find  the  statement  that 
they  have  "never  seen  marked  amblyopia,  ^  or  less, 
changed  by  operation,"-  — testimony  that  can  be  estab- 
lished by  nearly  all  oculists  when  they  have  tested  their 
cases  carefully,  both  before  and  after  the  operation  for 
squint.  I  cannot  recall  a  case  at  present  that  I  considered 
at  the  time  a  true  congenital  amblyopia,  in  which  the 
vision  has  improved.  I  consider  all  the  cases  of  reported 
improvement  in  the  vision  those  of  simple  amblyopia  ex 
anopsia,  the  cases  that  I  would  place  in  my  second  class. 
In  other  words,  simply  cases  of  reduced  vision  due  to 
suppression  of  the  visual  image  from  non-use  of  the 
retina.  This  is  a  physiological  function  of  the  retina  that 
is  simply  in  abeyance,  and  that  may  be  again  restored  by 
constant  use,  particularly  so,  when  positively  demanded, 
as  shown  in  the  oft-quoted  case  of  Dr.  Johnson,  of 
Paterson,  N.  J. 

Hansell  recognizes  congenital  amblyopia,  and  though 
he  does  not  classify  his  cases,  yet  states,  when  the 
amblyopia  is  high,  V.=2o/2oo  or  less,  that  the  vision  is 
not  improved  by  an  operation.  Landolt  offers  the  same 
testimony. 

Moreover,  another  fact  that  I  have  advanced  before  in 
favor  of  congenital  amblyopia,  and  one  which  seems  to 


Il6  STRABISMUS. 

me  rather  conclusive,  is  that  the  amblyopia  does  not 
increase  after  five  or  six  years  of  age,  the  earliest  age  at 
which  patients  can  be  tested  accurately.  To  give  an 
example,  say  in  a  patient  five  years  of  age,  the  vision  in 
the  good  eye  is  20/20  and  in  the  squinting  eye  is  reduced 
to  20/200  or  1/5  (assuming,  of  course,  that  vision  was 
20/20  in  each  eye  at  birth);  again,  on  testing  this  same 
patient  at  ten  years  of  age  or  later  in  life,  we  find  the 
vision  in  the  squinting  eye  still  20/200  —  that  is,  not  fur- 
ther reduced  after  five  more  years.  The  question  arises, 
why  does  not  the  amblyopia  increase  after  the  first  five 
years  of  life  if  it  is  due  to  non-use,  as  the  conditions  are 
the  same  for  the  eye  after  the  first  five  years  as  before  ? 

"One  swallow  does  not  make  a  summer,"  and  let  us 
for  a  moment  analyze  one  of  these  cases,  particularly  the 
case  furnished  in  full  as  an  illustration:  In  May,  1894, 
X.  B.  is  four  and  one-half  years  old ;  now,  periodic 
squint ;  two  years  more,  squint  now  marked  and  constant, 
V.=2o/ioo  in  L.  E.  This  is  the  first  true  test  of  vision. 
One  year  more,  V. — 20/50  with  glasses  ;  one  year  more, 
no  squint ;  two  years  more,  last  examination,  no  squint 
with  glasses  on,  V.* — 20/30.  Now  this  constant  squint  is 
not  cured,  only  corrected  with  glasses,  but  what  of  the 
restoration  of  vision?  When  the  little  fellow,  just  begin- 
ning to  know  his  letters,  not  accustomed  to  use  the  left 
eye,  was  tested,  V.=2O/ioo,  but  as  he  grows  older,  in  six 
years'  time,  with  full  correction,  thereby  improving  his 
vision  and  so  stimulating  his  fusion  force  to  fuse  the 
images,  we  have  the  vision  improved  to  20/30.  I  am 
sorry  to  say  I  must  consider  this  only  and  simply  a 
natural  result,  not  a  restoration  of  a  physiological  function 
or  a  psychical  suppression  of  the  retinal  image,  and  surely 
not  a  very  convincing  argument  for  the  total  absence  of 
congenital  amblyopia  in  another  case. 

It  is  undoubtedly  a  very  difficult  matter  to  "  draw  the 


STRABISMUS  OR  HETEROTROPIA. 


117 


line  "  between  that  of  true  amblyopia  and  that  from  non- 
use,  hard  to  say  positively  just  where  one  may  begin  and 
the  other  stop,  or  how  much  the  vision  may  be  reduced 
from  constant  disuse,  due  to  one  eye  constantly  turning 
inwards.  For  can  we  say  how  good  the  vision  may  be 
and  yet  indicate  a  true  congenital  amblyopia ;  but  it 
seems  to  me  that  nearly  all  observers  generally  "  draw 
the  line"  between  20/100  and  20/200,  or  less.  If  the 
vision  of  the  squinting  eye  is  20/100  or  better  it  is  prob- 
ably a  case  of  reduced  vision  from  non-use,  and  may  be 
very  materially  improved  by  glasses  and  the  educative 
treatment,  with  an  operation  if  necessary  ;  while,  on  the 
other  hand,  if  the  vision  is  found  to  be  20/200  or  less  in 
the  squinting  eye,  then  the  prospect  of  any  improvement 
in  the  vision  will  be  very  doubtful,  if  at  all,  though  we 
may  have  binocular  fixation,  the  visual  lines  parallel,  and 
the  squint  apparently  cured. 

It  is  very  evident  from  the  above  that  I  do  not  have 
much  confidence  in  the  restoration  of  vision  in  a  true 
amblyopic  eye,  but  it  must  be  understood  that  this  work 
represents  my  own  personal  experience  and  not  the  writ- 
ing of  others.  I  may  meet  some  cases  that  will  alter  my 
present  opinions  but  until  I  do  so  I  must  leave  the  reader 
to  form  his  own  conclusions.  In  this  connection  I  wish 
to  add  the  experience  of  one  or  two  who  have  been  very 
enthusiastic  on  this  subject.  In  1894  I  received  a  report 
from  my  friend,  Dr.  Titcomb,  of  fourteen  cases  of  con- 
vergent strabismus  in  children,  in  which  he  claimed 
some  excellent  results  in  the  correction  of  squint  with 
glasses,  and  in  a  certain  proportion  an  improvement  in 
the  vision.  His  report  is  as  follows  : 

Case    i     7  years    old.    Glasses  correct,   Hy.  V.  =  15/30  each. 

"  2     12         "  "  "  "  "      V,  =    15/30  " 

"       35"         "  "         no  use,       "    V.  =  20/40  amblyopia. 

"       46"         "  "         correct,      "    V.  =  20/40 


H8  STRABISMUS. 

Case    5     8  years,  old.  Glasses  correct,  Hy,  V.  =  20/40   each, 

"       66"  "  "            "             "    V.  =  20/30      " 

77"  "  "             "Ah.&  Hy.  V.  =  20/20      " 

(<       89"  "  "             '•     "       "    V.  =  20/50      " 

"       98"  "  "             "             "    V.  =  ? 

"     10     4     "  "  "             "             "    V.  =  ? 

"     ix     6     "  "  "            "            "    V.  =  20/50      " 

"126"  "  No  report,             "    V.  =  ? 

"133"  "  No  treatment,        ?    V,  =  ? 

"     14     4     "  "  Glasses  correct,          V.  =  20/40      " 

This  is  practically  the  substance  of  his  report  and  it 
shows  a  remarkable  per  cent,  of  correction  for  squint,  in 
fact,  almost  one  hundred  percent.,  and  he  was  very  much 
pleased  with  this  excellent  result.  But,  this  year,  1903, 
Dr.  Titcomb  has  sent  me  another  report,  in  which  he 
writes  that  he  cannot  trace  all  the  cases,  and  "  my  conclu- 
sion is  that  the  majority  of  cases  of  convergent,  in  chil- 
dren with  or  without  amblyopia,  but  having  marked 
refractive  error,  may  be  relieved  by  glasses  alone."  (The 
underscoring  is  my  own).  His  1903  report  is  as  follows  : 

Case  i  No  squint,  V.  imp,  to  20/20  each  eye. 

"  2      "       "       with  glasses. 

"  3  Operation  two  years  after  first  report. 

"  4  Squint  same,  says  does  not  wear  glasses. 

"  5  No  squint,  V.  improves  ? 

"  6  Operation,  after  wearing  glasses  eight  years, 

"       7     No  report. 
«       g      «       « 

"  9  "       " 

"  10  No  squint  with  glasses. 

"  ii  Result  unsatisfactory  ? 

"  12  Operation,  followed  by  marked  divergence. 

"  13  No  report. 

"  14  No  squint  with  glasses. 

These  records  are  very  interesting,  but  on  what  grounds 
does  he  base  the  assertion  of  "  with  or  without  amblyopia  " 
when  both  of  the  amblyopic  cases  (Nos.  3  and  4)  were  fail- 


STRABISMUS  OR  HETEROTROPIA.  UQ 

ures.  Furthermore,  this  second  report  only  shows  about 
thirty  per  cent,  of  successful  cases  with  glasses,  if  we  read 
it  carefully,  and  even  these  cases  seem  to  be  selected 
ones.  It  is  to  be  remembered  that  these  cases  were  under 
observation  several  months,  many  of  them  fully  under 
atropine  and  glasses,  and  yet  in  the  final  report  only  five 
show  a  good  result.  It  would  take  some  more  convincing 
argument  than  the  previous  conclusions  to  change  my 
opinions.  We  have  also  the  report,  published  in  the  N. 
Y.  Medical  Journal,  Jan.  2,  1897,  by  Dr.  Conners.  As  I 
know  he  is  familiar  with  my  work  I  have  great  confi- 
dence in  his  examinations.  He  gives,  in  his  report  which 
I  take  the  liberty  to  repeat,  these  cases : 

Case  i. —  Age  13.  Convergent  squint,  30°,  V.  R.  fingers  at  3  ft. 
L.  E.  20/20.  Operation  and  correction  of  the  squint.  Refraction 
4-  3.50  cyl.  90°.  By  exercise  and  exclusion  pad  R.  E,  =  20/40. 
(What  was  the  vision  of  R.  E.  with  glasses  before  operation  ?) 

Case  2. —  Age  25.  R.  E.  4/200,  L.  E.  20/20.  Convergent  squint, 
15  °.  Operation,  corrects  squint.  After  exercise,  R.  E,  20/100  with 
— 7,50  D.  (Did  this  case  have  amblyopia  or  myopia  in  the  R.  E  ?) 

Case  3. —  Convergent  squint,  30°.  R.  E.  15/15.  L.  E.  10/200. 
Operation,  tenotomy  and  shortening,  corrects  squint.  Exercise  and 
exclusion  pad,  3  months.  L.  E.  15/40,  with  +  2.  ^  +  .50  cyl.  90°. 
(Again  I  must  ask,  what  was  the  vision  with  glasses  before  the  oper- 
ation in  the  left  eye  ?  This  is  not  amblyopia.) 

Case  4. —  Age  38.  No  squint.  R.  E,  15/200,  with  +  2.50  ^+  2-75  cyl. 
90°.  L.  E.  15/15,  Hm.  +  2.  Q+  .75  cyl.  90°.  Exercise  and  exclu- 
sion pad.  R.  E.  15/40,  with  correction.  Reads  Snellen  No.  6. 
Treatment,  strychnia  and  phosphoric  acid. 

This  is  the  only  case  in  this  report  that  to  my  mind 
shows  any  improvement  in  an  amblyopic  eye,  yet  it  does 
not  seem  conclusive.  In  the  first  three  cases  the  doctor 
does  not  tell  us  what  the  vision  was  at  first  with  a  proper 
correction  of  the  refraction,  but  in  his  final  test  she  gives 
us  the  improvement  with  the  glasses.  Perhaps,  had  he 
fully  corrected  the  refraction  before  the  operations  he 


I2O  STRABISMUS. 

would  have  found  the  same  improvement.  I  regret  to  say 
I  would  need  some  more  positive  evidence  and  a  more 
full  report  before  I  could  conclude  that  these  cases  pre- 
sent any  serious  evidence  of  the  restoration  of  vision  in 
what  I  consider  a  true  amblyopic  eye. 

Finally,  I  report  a  case  under  my  own  care  of  improve- 
ment in  the  vision,  in  which  the  conclusions  are  obvious  : 

Irene  D.,  age  7,  1897.  Left  eye  turns  in.  Squint  periodic.  Hy.  = 
6,  D,  ord.  4-4.  D.  each.  1898.  V.  =  20/70,  with +  2, 50  D.  1900.  With 
correction,  V.  =  R.  E.  20/50,  L.  E.  20/70.  Ord.  wear  glasses  and 
cover  R.  E.  five  minutes  daily.  1902,  Has  Hy.  with  Ah.  axes  to 
nose,  with  correction,  R.  E.  20/30,  L.  E.  20/50,  no  squint  with  glasses, 
1903.  Has  stereoscopic  vision  and  bar  reading.  V.  with  correction.  R. 
.E.  20/20.  L,  E.  20/40+.  Trop.  R.  E.  25  °  up  ;  40°  in  ;  50°  out  ;  L.  E. 
up  ;  60°  in  ;  30°  out.  Add,  30°,  Abd.  14°. 

The  fields  of  fusion  and  version  show  why  this  child  had 
a  tendency  to  squint  and  the  continued  improvement  in 
the  vision  by  the  use  of  glasses  shows  the  counteracting 
effect  of  the  muscular  imbalance,  yet  this  is  not  a  case  of 
amblyopia  but  one  of  ex  anopsia. 

But  why  multiply  argument  on  argument  ?  The  matter 
will  still  stand  as  it  does  to-day.  Who  is  right  ?  Time 
alone  will  tell.  We  may  yet  know  the  truth  or  the  true 
cause  as  the  science  of  ophthalmology  advances,  but  even 
then  I  fear  the  axioms  will  be  denied  by  some.  I  am 
ready  to  be  convinced  either  way,  but  until  then  may  I  not 
conclude  in  the  language  of  Dr.  Drew:  "If  a  thought 
offered  or  conclusion  reached  excites  sufficient  interest 
and  reaction  in  your  minds  ....  to  call  forth  a 
free  discussion,  the  best  results  hoped  for  will  have  been 
obtained." 

Check  Ligaments.  The  portion  of  the  tissues  that 
forms  the  sheath  of  the  eyeball  and  the  muscles  ante- 
riorly (tenons  capsule),  has  an  attachment  all  around  the 
circumference  of  the  orbits  and  in  the  region  of  the  inter- 


STRABISMUS  OR  HETEROTROPJA.  I2i 

nal  and  external  canthus  becomes  much  thicker  than  in 
the  other  parts.  This  thicker  portion  is  called  the  check 
ligament.  They  are  attached  to  the  orbit  at  the  anterior 
part  and  the  posterior  portion  is  attached  to  the  fascia 
and  to  the  muscles  by  fibrous  bands.  These  ligaments 
are  supposed  to  hold  the  eyeball  steady  and  to  oppose  an 
excessive  action  of  the  muscles  when  contracted. 

Hansell  and  Reber  has  sug- 
gested that  the  attachments  of 
these  ligaments  may  have  some 
remote  cause,  from  their  anoma-  A" 
lous  arrangement,  in  the  failure 
to  correct  a  squint  by  a  free 
tenotomy.  It  is  possible  that 
these  ligaments  may  have  some 

influence    in    the     final     result    of    („)  INTERNAL  CHECK  LIGAMENT. 
Our  Squint  Operations,  but    in  all    (*)    EXTERNAL  CHECK  LIGAMENT. 

my  cases  the  rotation  of  the  eye  in  the  field  of  version 
has  been  so  free  that  I  do  not  think  these  ligaments 

o 

have  any  influence.  But,  in  this  connection,  I  would 
refer  the  reader  to  those  cases,  not  infrequently  seen, 
called  "  Congenital  absence  of  the  outward  movements 
of  the  eyes"-  — seeming  convergent  squint  —  where  I 
think  the  check  ligaments  may  have  a  very  important 
influence,  as  in  these  cases  there  is  a  very  decided  limita- 
tion of  the  outward  movement  of  the  eye  without  any 
evidence  or  history  of  paralysis.  I  do  not  think  this 
has  been  suggested  before, —  Leszynsky  has  reported  one 
of  these  cases  with  this  final  conclusion:  "Congenital 
arrest  of  development  affecting  the  external  recti  mus- 
cles or  possibly  a  faulty  insertion  of  those  muscles,"  but 
it  seems  to  me  that  an  abnormally  developed  check  liga- 
ment at  the  internal  canthus  would  more  clearly  produce 
the  symptoms  than  if  the  fault  was  in  the  muscles  or  their 
insertions.  I  report  a  case  that  was  examined  by  myself 


122  STRABISMUS. 

that  seems  to  indicate  the  influence  of  these  check  liga- 
ments on  the  rotation  of  the  eye. 

Miss  A.  R.,  age  13.  Convergent  squint,  each  eye,  static  condi- 
tion, 15°  inward.  Noticed  in  first  six  months  of  life.  Each  eye  will 
follow  the  test  object  inward  but  not  outward  beyond  the  first  posi- 
tion ;  does  not  complain  of  diplopia  ;  turning  the  head  slightly  to 
the  right  or  left,  V.  =20/15  in  each  eye.  With  red  glass  before  one 
eye  she  has  slight  crossed  diplopia.  Refraction  hyperopic,  less  than 
i.  D.  Fields  normal  ;  convergence  normal,  and  fusion  near  point 
seems  at  two  inches  with  binocular  fixation,  but  she  does  not  have 
binocular  vision  ;  has  no  field  of  fusion  ;  perimeter  shows  conver- 
gence of  fifteen  degrees  with  fixation  generally  in  the  right  eye, 
Tropometer.=  R.  E.  20°  up  ;  50°  down  ;  15°  in  ;  o°  out. 
"  =  L.  E.  30°  up ;  45°  down  ;  35°  in  ;  o°  out. 

This  examination  seems  to  show  a  certain  limitation 
of  the  outward  movements  of  the  eye  that  may  be  due  to 
a  congenital  shortening  of  the  internal  check  ligament 
which  restricts  the  outward  movement  to  a  point  slightly 
inside  of  the  first  position,  with  fixation  of  one  eye  by 
rotation  of  the  head. 


CHAPTER  VIII. 

ILLUSTRATIVE     CASES. 

THIS  series  of  cases  is  given  in  detail  to  show  more 
fully  the  method  of  examination,  the.  indications  for  the 
operation,  and  the  final  results.  I  have  tried  to  illustrate 
in  this  way  the  various  conditions  of  heterophoria  and  of 
heterotropia  that  may  be  met  with  in  the  usual  office  prac- 
tice. All  of  them  had  the  refraction  carefully  corrected 
by  myself,  or  by  others  fully  competent  to  do  so,  but 
wearing  their  full  correction  did  not  give  them  relief  from 
their  asthenopic  symptoms.  A  careful  comparison  of  the 
details  of  these  examinations  made  before  the  operation 
and  then  afterwards  was  very  instructive  to  me  as  I  was 
interested  in  the  binocular  effect,  that  is  to  say,  the  effect 
on  the  muscles  of  the  non-operated  eye.  In  nearly  all  of 
these  cases  I  could  note  the  change  that  occurred  and 
that  seems  to  me  a  physiological  process  very  difficult  to 
explain  unless  we  can  see  some  psychological  influence 
acting  on  the  muscles  at  the  same  time. 

CASE. —  Paralysis  of  Convergence.  J.  D.,  age  45.  Seen  at  clinic, 
1902.  Had  an  attack  of  hemiplegia,  left  side,  says  he  is  much  better 
under  treatment.  Left  leg  only  affected  now.  Complains  of  diplo- 
pia  when  on  the  street.  .Cannot  read;  ¥.  =  20/20,  each,  and  he 
seems  to  have  binocular  vision  at  twenty  feet,  but  he  cannot  con- 
verge the  eyes  to  a  point  nearer  than  one  foot,  when  he  has  crossed 
diplopia.  The  eyes  seem  to  fix  at  that  point.  Has  Add.  =  8°  ;  Abd, 
4°.  Tropometer,  10°  up  ;  60°  down ;  55°  out ;  and  50°  in.  This 
examination  shows  that  the  associated  movements  of  the  eyes  are 
normal ;  his  field  of  fusion  well  balanced  but  small,  and  his  field  of 
version  shows  a  tendency  to  kataphoria.  It  is  evident  in  this  case 
the  cause  of  the  trouble  must  be  central. 


124  STRABISMUS. 

CASE. —  High  Myopia  with  Hyperphoria.  Mrs.  H.,  under  my  care 
the  past  nine  years.  Has  myopia  of  18  D  ;  V.  R.  =  20/30  V.  L.  = 
10/200,  due  to  large  macular  choroiditis.  These  changes  at  the 
macula  have  become  perfectly  quiet  ;  has  good  fixation  at  twenty 
feet  ;  right  hyperphoria  of  8°,  with  an  exophoria  of  4°,  by  Rod  test  ; 
Add.  6°  ;  Abd.  8°.  In  1895  had  tenotomy  of  R.  Sup.  and  L.  Ext.  De- 
cided improvement. 

CASE. —  Myopia  with  Exophoria.  Mrs.  R.  H.  P.,  age  38.  V.  R.  E. 
=  20/40,  L.  E.  =  20/15,  with  correction  of  the  myopia  and  Am.  ; 
slight  hyperphoria,  =  i°  ;  Exophoria  =  10°  Rod  test.  Supraduc- 
tion,  R.  3°;  L.  4°.  Add.  6°;  Abd.  15°,  Tropometer  25°  up;  450 
down  ;  45°  in  ;  50°  out,  each  eye.  Operation:  Tenotomy,  both  ex- 
terni.  This  case  has  a  long  corneal  curve,  showing  increasing  myo- 
pia, but  at  the  present  time  has  had  no  symptoms  of  muscular 
asthenopia  and  illustrates  the  effect  of  correcting  the  lateral  balance 
first, 

CASE. —  Myopia,  with  Exophoria  and  Kataphoria.  Mrs.  B.  F.  M. 
1901.  Cannot  use  the  eyes  and  has  various  nervous  symptoms. 
V. =20/15,  witn —  5-  D.  each.  Add.  15°;  Abd.  12°;  Exophoria— 5  °; 
Oph.  shows  My.  of  5.  D.  and  no  staphyloma,  radius  of  cornea, 
=  7. 5mm.  Tropometer,  10°  up;  60°  down;  40°  in;  45°  out. 
Divergence  under  cover  test  and  at  near  point.  Operation:  Shorten- 
ing of  both  Interni.  1903.  Decided  improvement  in  nervous  and 
general  condition.  Add.  30°;  Abd.  8°,  Trop.  10°  up;  60°  down; 
40°  in;  40°  out.  The  tropometer  shows  the  weakness  of  both 
superior  or  the  tendency  of  both  visual  lines  to  tend  below  the  hori- 
zontal plane  (Kataphoria).  Lateral  motion  perfect,  so  I  ord. —  5.  D. 
C3  prisms  3/4°  base  up  over  each  eye.  A  shortening  of  both  supe- 
rior would  obviate  the  use  of  these  prisms  but  as  she  has  improved 
so  much,  no  further  interference  is  necessary. 

CASE  2925.  —  Myopia  with  Exophoria.  1901.  Mr.  G.  W. ,  age  44. 
Dentist,  cannot  work.  Refraction,  My.  w.  Am.  90°  ;  ¥.=20/30, 
each;  Exophoria,  8°.  Trop.  40°  in;  45°  out.  Add.  20°;  Abd.  12°. 
His  excessive  abduction  indicates  tenotomy  and  I  did  a  partial  tenot- 
omy of  the  L.  Externus,  cutting  all  the  upper  and  lower  part  of  the 
tendon.  1902,  Better,  same  operation  on  the  R.  Externus.  He  still 
shows  some  exophoria  and  I  shorten  the  R.  Internus.  Slight  hyper- 
phoria. Result,  complete  relief.  Add.  20° ;  Abd.  8°.  Trop,  45°  in; 
45  °  out.  An  interesting  feature  of  this  case  was  the  fusion  near 
point,  at  three  inches,  while  he  had  an  exophoria  of  8°  at  distance, 


ILLUSTRATIVE  CASES.  125 

but  I  think  this  was  due  to  the  increased  illumination  and  in  this  way 
a  greater  stimulation  of  the  fusion  force.  It  also  shows  the  effect  of 
these  operations  when  this  function  is  active,  and  Stevens'  suggestion, 
that  a  tenotomy  of  the  externus  has  much  less  effect  on  the  action 
of  rotation  than  that  of  a  similar  operation  on  the  internus. 

CASE  594. —  M.  Myopia  with  Convergent  Squint,  First  Class,  and 
Amblyopia.  Feb.,  1903.  Miss  F.  E. ,  age  14.  R.  E.  w. —  7.  D.Q  — 
1.50  cyl.  ax.  180  °=2o/3o.  L.  E.  w. —  7.^  —  2.50  cyl.  ax.i6o  c=2o/ioo, 
Short  radius  of  corneal  curve.  No  changes  at  fundus.  Onset, 
at  birth.  Excessive  convergence.  Here  are  all  the  essentials  for 
divergent  squint,  high  myopia  and  amblyopia,  yet  the  eyes  turn  in. 
I  can  see  no  other  reason  or  cause  than  the  weakness  of  the  externi. 
Operation:  Shortening  of  the  externus  and  tenotomy  of  the  internus. 
Nov.,  1903.  V.=same.  Trop.  shows  good  field  of  version  except 
weak  inferior  of  the  L.  E. 

CASE  2593.  —  Myopia  with  Convergent  Squint,  Second  Class. 
1899.  Mr.  B  R. ,  age  25.  Left  eye  turns  in;  no  binocular  vision. 
Refraction,  My,  6.  D,  with  Am.  ax.  90°.  V.  R.  =20/15;  V.  L.  =2o/ 
30.  Convergence,  40°.  Operation:  Shortening  of  the  left  externus 
and  complete  tenotomy  of  the  left  internus.  1902.  Result,  perfect. 
Add.  25°;  Abd.  6°.  Binocular  vision,  as  shown  by  the  stereoscope 
and  bar  reading.  After  the  operation  the  Trop.  shows,  30°  up;  55° 
down;  55°  in;  55°  out,  each  eye.  This  case  is  very  interesting 
from  the  high  myopia  with  convergent  squint  completely  corrected 
by  operation  on  the  squinting  eye  only,  with  perfect  binocular  vision. 
It  must  point  to  weak  externi  as  the  essential  cause,  as  I  cannot  see 
what  neuro-pathology  can  have  to  produce  the  squint,  nor  how  the 
operation  could  have  influenced  the  action  of  the  innervation  in  the 
field  of  version. 

CASE  2918.  —  Convergent  Squint,  Second  Class.  Onset,  late  in 
life.  1901.  Mr.  S,  G.  A,,  age  32.  Asthenopic  symptoms  several 
years,  after  an  accident?  The  left  eye  turns  in.  V.  =20/15.  each. 
Refraction,  Em.  Careful  testing  shows  horn,  diplopia  of  40°.  Trop. 
50°  in;  30°  out,  each  eye,  Operation:  Shortening  of  left  externus, 
leaving  horn.  dip.  20°.  Then  tenotomy,  left  internus.  Result,  per- 
fect. One  year  after,  perfect  binocular  vision;  no  asthenopic  symp- 
toms. Esophoria,=i/2°.  Add.  12°;  Abd.  3°.  Trop.  45  °  .in;  45° 
out.  This  case  shows  many  years  of  muscular  asthenopia  or  eso- 
phoria,  eventually,  at  the  age  of  30  changing  to  convergent  squint 
(simply  one  of  degree)  and  the  examination  of  the  field  of  version 


126  STRABISMUS. 

shows  that  the  accident  was  not  the  cause  nor  was  it  a  case  of  the 
so-called  "  paresis  of  divergence." 

CASE  2680.  —  Convergent  Squint,  Second  Class.  Master  S.  C.  L, 
age  6.  Onset,  3  years.  L.  E.  turns  in;  V.=2o  15,  each.  Refrac- 
tion, Hy.  w.  Ah.  90° .  Operation  :  Shortening  of  the  L.  Externus  and 
tenotomy  of  the  L.  Internus.  Result,  perfect  cosmetic;  seems  to 
have  binocular  vision  at  distance  and  good  stereoscopic  vision.  Add. 
20°;  Abd.  15°?  Tropometer,  R.  E.  30°  up;  50°  down;  50°  in; 
40,  out.  L.  E.  40°  up;  50  down;  60°  in;  40°  out.  This  shows 
slight  hyper-esophoria  still  remaining.  1903.  This  boy  has  no 
squint  and  good  binocular  fixation. 

CASE  2470.  —  Convergent  Squint,  First  Class.  Mr.  J.  E.  B.,  age  37. 
1899.  R.  E.  turns  in.  Operation  16  years  ago  with  no  change  in 
the  visual  line.  V.  R.  =20/20  ;  V.  L.=  fingers  at  two  feet ;  Hm. 

1.  D. ,  total  Hy.  4.  D,     The  left  eye  shows  a  high  degree  of  astigma- 
tism, but  no  improvement  with    cylindric   glasses  ;  Trop.   R.  E.  40° 
in;  40°    out.     L.  E.  50°  in;  35°   out.     This  shows    the  fault  to  be 
principally  in  the  left  externus,  so  I  shorten  this  muscle  and  cut  the 
tendon  of  the  internus.     Result,  1903,  four  years  after,  perfect  cos- 
metic.    Says  he  has  some  crossed  diplopia,  due  to  eccentric  fixation. 
V.=  same  as  at  first  examination. 

CASE  2464. — Convergent  Squint,  Second  Class,  corrected  by  glasses. 
Miss  M.  V.  W.,  age  7.  Squint  alternating.  ¥.=20/15  each,  with  + 

2.  Q  +,1.90°.     With  this  glass  no  convergence  of  the  visual  lines. 
Four  years  after,  1903,  conditions  the  same.     No  squint  with  glasses, 
but  the  tendency  to  esophoria   is  the  same,  as  Add.  15°;  Abd.  i  °, 
and    Trop.    R.  E.  55°  in;  48°  out.     L.  E,  50°  in;  45°  out.     This  is 
a  good  illustration  of  those  cases  said  to  be  cured  with  glasses.     It 
will  be  noted  that  the  muscles  of  abduction  are  not  very  weak  in  the 
field  of    version  and  so  the  increased   visual    power  by    the  use  of 
glasses  and  the  relief  of  the  strain  on  the  accommodation,  corrects 
the  inward  tendency  but  the  primal  cause  remains. 

CASE  1929. — kSame.  Convergent  Squint,  Second  Class.  Miss  J.  P. 
D.,  age  7.  1896.  Onset,  at  first  year  of  age.  L.  E.  turns  in.  V.  under 
atropine,  with  +  6.50  D.  =R.  E.  20/30  ;  L.  E.  20/50.  Under  atropine 
the  squint  stops,  and  afterwards  she  has  Hm.  2.50  D.  This  glass 
ordered  and  the  child  has  perfect  fixation  but  no  binocular  vision. 
Ophthalmometer  shows  2.  D.  of  astigmatism  not  shown  by  retinos- 
copy  nor  will  she  accept  cylindric  glasses.  1901.  Accepts  cylindric 
glasses  and  with  correction  V.  improves.  R.  E.  =20/15,  L.  E.  = 


ILLUSTRATIVE  CASES. 


127 


20/20.  Still  no  binocular  vision.  1903.  Cover  test,  and  with  red 
and  green  glasses  left  eye  turns  in,  showing  esophoria  4°,  but  with 
glasses  seems  to  have  perfect  fixation  at  twenty  feet,  also  has  stere- 
oscopic vision  but  not  bar-reading.  Trop.  R.  E.  60°  in  ;  50°  out; 
L.  E.  50°  in  ;  50°  out.  At  times  her  Add.  shows  12°  and  Abd.  12°, 
not  constant.  This  case  is  reported  as  one  showing  Bonders'  theory 
from  the  correction  of  accommodation  and  convergence  and  shows 
also  the  supposed  restoration  of  vision,  20/50  to  20/20.  Further- 
more, this  case  may  illustrate  Worth's  theory  as  the  fusion  force  is 
very  low,  but  is  simply  due  to  the  high  hyperopia.  When  we  examine 
the  rotation  in  the  field  of  version  we  find  the  true  cause  of  her  ten- 
dency to  squint  held  in  check  by  the  increased  fusion  force  caused 
by  the  correction  of  the  refraction  by  glasses.  Still  the  prime  fault 
remains. 

CASE.  —  Divergent  Squint,  First  Class.  1899.  Miss  C.  S.,  age  15. 
R.  V. =20/15,  Ah.  .50  cyl-  9°°-  L.  E.  20/200,  imp.  +  1.50  D.  cyl. 
90°.  Operation  :  Shortening  left  internus  and  tenotomy  left  exter- 
nus.  Complete  cosmetic  result  but  no  improvement  in  vision.  Bi- 
nocular fixation.  Here  we  have  divergent  squint  with  hyperopic 
astigmatism.  I  can  see  no  reason  for  this  except  a  muscular 
anomaly. 

CASE  1272.  —  Divergent  Squint  with  Amblyopia.  Miss  C.,  age  34. 
1892.  Onset,  when  baby.  Occipital  head  pain.  Refraction,  All- 
go0 .  R.  V.  =20/40.  +  L.  V.=2o/2oo.  Glasses  of  no  use.  Crossed 
diplopia,  26°.  Perimeter,  left  eye  turns  out  45°.  Operation  :  Com- 
plete tenotomy  of  L.  Ext.  1900.  Eight  years  after,  perfect  cosmetic 
result.  No  binocular  vision.  Vision  same  as  at  first  examination. 
This  case  only  presents  one  condition  to  me,  the  very  weak  Int. 
more  pronounced  in  the  Amblyopic  eye. 

CASE.  —  Divergent  Squint,  after  an  Operation.  Miss  A.  O.,  age  16. 
1903.  States  that  I  operated  on  the  R.  E.  nine  years  ago,  proba- 
bly by  simple  free  tenotomy  ;  eyes  did  well  for  a  time,  then  the  R.  E, 
turned  out.  It  is  now  very  prominent.  This  case  shows  the  danger 
of  too  free  a  tenotomy  on  the  Internus  and  the  Trop.  shows  R.  E. 
20°  in  ;  50°  out.  L.  E.  50°  in  ;  45°  out.  Under  ether  I  tried  to  ad- 
vance the  Internus  ;  it  was  found  at  the  inner  canthus  and  not 
attached  to  the  sclera  in  any  way  ;  it  was  brought  forward  and 
attached  to  the  conjunctiva  and  a  tenotomy  of  the  externus  per- 
formed. The  result  showed  slight  outward  squint.  Eye  less  promi- 
nent and  Trop.  R.  40°  in  ,  40°  out. 


128  STRA  B  ISM  US. 

CASE  432  W. —  Divergent  Squint  or  Exophoria  ?  Mr.  F.  W.,  age 
38.  Tendency  of  the  eyes  to  diverge  since  a  boy.  Has  good  con- 
verging power.  Dizzy  spells.  R.  E.  turns  out  almost  constantly. 
R.  V.=2o/2o,  w. — .25  cyl.  45 °. =20/20 -K  L.  V.  20/40,  w. — .75  = 
20/20+.  Refraction,  slight  myopia.  Operation  :  Shortening  of  L. 
Internus  and  tenotomy  of  Ext.  One  year  after,  perfect  result ;  V. 
improves  to  20/15.  Here  is  an  exophoric  condition  slowly  chang- 
ing to  a  divergence  with  almost  emmetropic  refraction.  It  shows  the 
close  relation  between  heterophoria  and  squint  and  must  have  been 
due  to  the  weakness  of  the  Interni. 

CASE  1388.  —  Exophoria  with  Hyperopia  and  Amblyopia.  Mrs.  J. 
H.,  age  35,  is  a  case  of  typical  squint  of  the  first  class  without  any 
deviation  of  the  visual  lines.  Has  had  constant  asthenopic  symp- 
toms since  a  child.  R.  ¥.=  20/70,  w.+  3.5o3+  75  cyl.  90°=  20/40. 
L.  V.  20/200,  accepts +  4.50  D.  Has  worn  these  glasses  constantly 
since  1901.  Has  exophoria  of  6°.  Add.  i5°;Abd.  20°.  Trop.  R0  E. 
40°  in  ;  50°  out ;  L.  E.  50  °  in  ;  45  °  out.  Tenotomy  Right  Exter- 
nus.  1903.  Very  much  better.  Trop.  R,  E.  45°  in  ;  45°  out  ;  L. 
E.  same.  Add.  20° ;  Abd.  15  °.  It  will  be  noted  that  in  this  case  the 
eye  turns  out  while  she  has  all  the  conditions  for  convergent  squint. 
From  the  examination  of  the  duction  I  thought  a  tenotomy  of  the 
very  strong  externi  would  be  the  best.  The  final  result  and  relief 
was  very  satisfactory, 

CASE  464  \V.  —  Exophoria  with  Hyperopia.  Mr.  W.  L.,  age  8.  1898. 
V.=  20/30,  w.+  1.50  D.  =  20/15,  each  eye.  Add,  6°;  Abd.  8°. 
Glasses  of  no  assistance.  Operation  :  Shortening  of  Left  Internus. 
1901.  At  school,  no  asthenopia,  Hm.  +  i.  D.  Add  15°;  Abd,  8°.  We 
may  call  this  excess  of  divergence  but  the  essential  cause  is  weak- 
ness of  the  Interni  as  indicated  by  the  operation. 

CASE.  —  Exophoria.  1900.  Miss  A.  P.,  age  26,  Pain  in  the  head, 
back  of  the  neck  and  shoulders,  nausea  and  car-sickness.  Had 
glasses.  Refraction,  Ah.  ax.  90°.  V.  20/15,  each.  Exophoria  8°. 
Add.  6°;  Abd  8°;  superduction  i°,  each.  Trop.  45°  in  ;  50°  out  ; 
Operation:  Shortening  Left  Internus.  Result,  1903,  Add.  15  °.  Abd,  5°. 
Trop.  45°  in  ;  40°  out.  Has  had  no  symptoms  of  asthenopia  since 
the  operation. 

Hyperphoria  with  Hypophoria.  Mr.  W.  E.  P.,  age  45.  1899.  Re- 
fraction. Hy.  with  Ah.  90°.  Add.  15° ;  Abd.  8°.  R.  Superduction,  8°. 
L.  Subduction,  8° .  Presbyopic.  Operations:  Tenotomy  of  R.  Sup.  and 
L.  Inf.  Result,  superduction  4°,  each  eye,  complete  relief.  It  is 


ILLUSTRATIVE  CASES. 


129 


noticeable  in  this  case  how  late  in  life  the  muscular  symptoms  began 
to  cause  the  asthenopia.  1903.  Has  had  no  further  trouble  with  the 
eyes. 

CASE  2629.  —  Esophoria,  improved  with  Prisms.  Mr.  H.  B.  A.,  age 
29.  Refraction,  Ah.  180°,  V.=  20/1 5  each  ;  Add.  40°;  Abd.  6°.  Trop. 
50°  in  ;  40°  out,  each  eye.  This  case  shows  a  decided  tendency  to 
Esophoria,  but  as  the  outward  rotation  in  the  field  of  version  seemed 
equal  I  ordered  full  correction  of  the  refraction,  combined  with  prisms 
2°  each,  bases  out  over  each  eye.  One  year  after  he  was  very  com- 
fortable with  these  glasses  but  I  think  a  shortening  of  an  Externus 
would  have  been  the  best  procedure.  He  declined  to  have  an  oper- 
ation. 

CASE  2621.  —  Esophoria.  Miss  B.  H.,  age  30.  1899.  Glasses  by 
others,  no  relief.  Refraction,  Ah.  90°.  V.—  20/15  each.  Add.  20; 
Abd.  i°.  Esophoria,  =  5  °.  Operation:  Shortening  R.  Externus.  1902, 
reports  complete  relief  since  operation. 

CASE,  — Esophoria.  Constant  pain  in  the  head  and  cannot  use  the 
eyes  for  reading.  Refraction,  Ah.  +  37  ax.  90  .  V.  =  20-15.  each.  Add. 
30°,  Abd.  5°.  Rod,  Esophoria,  12°.  Trop.  R.  E.  52°  in  ;  55°  out  ;  L. 
E.  62°  in;  45° out.  Depending  on  the  test  with  prisms  and  the 
tropometer  I  shorten  the  left  externus.  Operation  stops  all  pain  in 
the  head.  Now,  Add.  25°,  Abd.  8°.  Trop.  R.  E.  50°  in  ;  50°  out. 
L.  E.  55°  in  ;  48°  out.  Esophoria,  10°.  It  will  be  noted  in  this 
case  that  the  esophoria,  as  shown  by  the  rod  test  remains  the  same 
almost  as  before  the  operation,  showing  that  we  cannot  depend  on 
an  examination  that  deprives  the  eyes  of  the  guiding  sensation. 

CASE  2832.  —  Esophoria,  with  Amblyopia.  Mr.  W.  J.  C.,  age  20. 
Refraction,  Anisometropia.  R.  E.  w,-j-  1.50^4-  1.50  cyl.  9o°=2o/i5, 
L.  E.  w.+ 4.  =  20/200,  No  improvement.  The  L.  E.  turns  in  under 
the  cover  test.  Horn,  diplopia,  6°.  Add.  10°;  Abd.  o°,  Trop.  50°  in  ; 
45°  out ;  L.  E.  50°  in  ;  35°  out.  Operation  :  Shortening  Left  Exter- 
nus. Result,  perfect  fixation.  Abduction  2  °.  This  case  is  on  the 
borderline  of  convergent  squint  of  the  first  class,  yet  with  the  ambly- 
opia  still  shows  some  fusion  power. 

CASE  1244. —  Esophoria,  with  My.  and  Am,  1893.  Mrs.  C.  M.  J., 
age  36.  Glasses  6  years,  no  relief.  L.  =  20/15,  w'tn  correction, 
each  eye.  Add.  40°;  Abd,  5°.  Esophoria,  3°.  Operation,  tenot- 
omy  L.  Internus.  Some  shock  after  operation.  1893.  Much  better. 


130 


STRABISMUS. 


igoi.  Complete  relief.  In  this  case  we  have  an  esophoria  associ- 
ated with  myopia,  not  to  be  accounted  for  on  the  usual  theories  of 
squint. 

CASE  2065. —  Esophoria,  with  Myopia.  1897.  Mr.  H.  A.,  age  47,  artist. 
Must  close  one  eye  to  see  well.  My.=2.  D.  V.=2o/i5.,  w'tn  correc- 
tion. Add.  30°  ;  Abd.  3°.  Operation  :  Shortening  Left  Externus.  After- 
wards, V.  is  steady,  with  binocular  vision  and  fixation.  Add.  24°; 
Abd.  6°.  This  case  shows  simple  myopia  and  yet  we  have  the  ten- 
dency for  the  eyes  to  turn  inward.  Is  it  not  due  to  weak  externi  ? 

CASE  2920. —  Esophoria,with  Hyperphoria.  1901.  Mr.  W.  E.  S.,  age 
38.  Refraction,  Am.  90  .  Glasses  some  years,  no  relief,  V.  R.=2o/i5, 
L.  20/30,  with  correction.  Add.  20° ;  Abd.  2°,  Esophoria,  4°,  L.  Hy- 
perphoria, i°.  R.  Supraductiono0,  L.  4°.  Trop.  R.  E.  25°  up  ;  50° 
down;  55°  in  ;  45°  out.  L.  E.  30°  up  ;  50°  down  ;  50°  in  ;  40°  out. 
Operation  :  Shortening  left  externus  and  tenotomy  left  superior.  1902. 
Binocular  vision,  Add.  12°;  Abd.  4°.  Still  has  a  slight  hyperphoria. 
V.  has  improved,  no  asthenopia.  Trop.  35°  up  ;  50°  down  ;  50°  in  ; 
50°  out,  each  eye.  This  last  examination  shows  a  normal  balance 
in  the  fields  of  fusion  and  of  version. 

Case  3006. —  Amblyopia,  no  Squint.  J.  B.,  age  30.  Perfect  fixation,  no 
bar  reading.  R.  E.  ¥.=20/200  not  improved  with  glasses.  L.  E.  V.= 
20/30,  w.+.socyl.  i8o°=2o/i5,  Esophoria,  3°,  Add. 4°,  Abd. 4°.  Trop. 
25°  up  ;  50°  in  ;  45°  out.  This  case  has  all  the  essentials,  as  formerly 
advanced,  of  convergent  squint,  of  the  first  class,  yet  the  right  eye 
does  not  turn  in,  nor  has  there  been  any  change  in  the  vision  of  that 
eye  since  birth.  I  think  this  must  be  congenital  amblyopia  and  yet 
the  appearance  of  the  retina,  with  the  ophthalmoscope  was  perfectly 
clear.  It  is  further  evident  that  the  lateral  balance  of  the  eyes  is 
almost  normal  and  while  the  rod  test  shows  esophoria  the  duction 
test  shows  exophoria  and  the  tropometer  shows  normal  movements 
in  the  field  of  version.  In  the  field  of  fusion  we  find  the  reason 
why  this  case  does  not  squint,  as  adduction  is  the  same  as  abduc- 
tion. Now  I  do  not  think  that  this  case  will  ever  squint,  but,  if  with 
the  above  condition  we  associate  weak  externi,  then  the  amblyopic 
eye  will  quickly  turn  in  during  childhood. 

Case. —  Anaphoria.  MissJ.B.  Asthenopia  past  two  years.  Glasses  of 
no  assistance.  V.=2o/i5,  each.  Will  not  accept  any  glass.  She  says 
she  always  likes  to  look  up  and  the  eyes  feel  better  when  she  does  so, 
also  tends  to  draw  back  the  head.  Add.  20°  ;  Abd.  8° .  Trop.  40°  up  ; 


ILLUSTRATIVE  CASES.  131 

50°  down;  55  in;  50°  out.  Ordered  prism  i°  base  down  over 
each  eye.  (See  also  case  of  anaphoria  reported  with  operation  in  the 
chapter  on  hyperphoria). 

Case  3570. —  Left  Hyperphoria  and  Esophoria  ?  Mrs.  D,  C.,  age  25. 
Has  had  trouble  with  the  eyes  since  she  was  ten  years  old.  Has 
been  under  the  care  of  many  others,  wearing  glasses.  When  she 
came  to  my  office  she  was  wearing  R.  E.  prism  7°,  base  in  ;  L.  E. 
prism  4° ,  base  down.  Says  these  glasses  gave  her  more  comfort  than 
others  but  she  is  not  relieved.  She  is  still  very  nervous,  pain  in  the  head 
and  the  back  of  the  neck  ;  reading  causes  nausea  and  she  becomes 
dizzy.  R.  E.  V. =20/15,  imP-  w-+-5°  cyl-  8°°-  L.  E.  ¥.=20/15,  imp, 
w.-r.5o  cyl.  70°.  Objective  examination  shows  this  glass  to  be  cor- 
rect and  so  ordered.  The  left  eye  appears  to  stand  above  the  fel- 
low eye,  a  slight  vertical  squint  or  left  hyperphoria.  Esophoria  = 
5°,  hyperphoria  =4°,  by  the  rod  test.  Prism  test  shows,  R.  E.  3°, 
L.  E.  6°,  superduction ;  Add.  20°  to  25°,  Abd.  14°,  each  eye. 

Tropometer  =  R.  E.  30°    up;  60°    down;  50°    in;  55°  out. 
"  =L.   E,  35°    up;  50°    down;  65°    in;  40°  out. 

Operation  :  Shortening  of  the  left  inferior  with  the  catgut  suture 
Final  examination.  Result  :  Head  feels  much  better  in  every  way. 
Orthophoria  by  the  rod  test.  Superduction  3°,  each  eye;  Add.  20°, 
Abd.  10°  each.  Tropometer,=  30°  up;  60°  down;  55°  in;  50° 
out,  each  eye. 

Remarks.  There  are  several  points  of  interest  in  this 
case.  The  history  of  long  continued  muscular  asthenopia, 
showing  that  the  condition  was  partly  congenital !  The 
fact  that  she  could  wear  the  prism  of  7°,  over  the  internus 
was  surprising  when  we  note  the  field  of  version,  but  I 
think  the  most  comfort  she  could  have  found  from  her 
glasses  was  due  to  the  prism  over  the  left  eye.  Her  astig- 
matism, very  unusual  in  the  position  of  the  axes,  seems 
not  to  have  been  corrected.  The  Tropometer  shows  the 
vertical  imbalance  but  also  esophoria.  Following  the 
suggestions  of  others  I  operated  on  the  left  inferior  and 
this  seems  to  have  corrected  the  lateral  imbalance.  It  is 
evident  that  the  fault  was  simply  and  only  in  the  inferior 
of  the  left  eye  which,  in  my  opinion,  was  congenitally  weak. 


132 


STAABJSMUS. 


CASE. —  Frontispiece:  In  considering  the  cause  of  squint  some 
years  ago  I  doubted  if  the  illiterate  races  could  have  squint  of  the 
second  class,  that  is,  squint  in  which  hyperopia  might  be.  the  cause. 
It  occurred  to  me  that  all  squint  of  these  ignorant  people,  who 
seldom  use  the  visual  power  at  the  near  point,  must  have  amblyopia 
or  squint  of  the  first  class,  as  hypermetropes,  who  seldom  call  into 
action  the  accommodation  and  convergence,  could  not  have  any  ten- 
dency to  squint  unless  there  was  some  other  cause.  On  a  visit  to 
Charleston,  S.  C.,  in  the  summer  of  1902,  Dr.  Hallock,  of  that  city  gave 
me  the  photographs  of  the  individual  shown  in  the  frontispiece  of  this 
book,  stating  that  the  boy  had  been  operated  on  and  that  it  was  a  com- 
plete failure.  Now  this  case  fully  illustrates  squint  of  the  second  class 
in  an  ignorant  farm  hand  who  has  never  used  the  eyes  at  the  near 
point  —  except  to  look  for  a  watermelon  —  and  yet  it  is  evident 
that  the  vision  is  normal  in  each  eye  with  a  decided  squint  of  the 
alternating  variety.  Had  this  case  been  considered  in  reference  to 
the  muscular  condition,  in  which  the  evidence  of  the  weakness  of  the 
externi  is  apparent,  and  had  a  shortening  or  an  advancement  been 
performed  on  both  externi,  and  then  a  tenotomy,  if  needed,  his  squint 
would  have  been  corrected  with  probably  binocular  vision. 


CHAPTER  IX. 

THE     INDICATIONS     FOR     OPERATING     IN     LATENT    OR     FIXED 

SQUINT. 

IT  has  always  seemed  to  me  difficult  to  decide  the 
question  :  Is  it  best  to  operate  on  the  ocular  muscles  for 
heterophoria  and  heterotropia,  and,  if  so,  what  is  the 
best  operation  to  perform  ?  I  think  the  decision  as  to 
the  necessity  for  an  operation  is  a  very  important  one, 
and  the  determination  of  what  operation  to  perform  is 
decidedly  more  important.  I  do  not  think  nor  contend 
that  all  our  indications  point  to  one  operation,  but  that 
all  our  operations  must  be  modified  or  elaborated  accord- 
ing to  the  results  given  to  us  by  the  tests  of  the 
relative  power  of  the  straight  muscles  of  the  eye.  Yet, 
if  we  accept  the  proposition  that  all  forms  of  heterophoria 
and  heterotropia  are  due  to  a  deficiency  in  power  of 
some  one  or  more  muscles  as  the  primal  cause,  then 
that  deficiency  should  be  carefully  looked  for  and  cor- 
rected as  the  first  steps  in  our  operative  procedure. 
Hence,  the  suggestion  for  an  operation,  to  my  mind,  is 
ever  present  in  all  these  cases,  even  if  they  can  be  cor- 
rected by  glasses,  but  as  to  the  performance  of  an 
operation  that  can  be  left  to  the  decision  of  the  patient. 
My  reasons  for  this  is  that  all  cases  of  heterotropia  are 
simply  heterophoria  in  greater  or  less  degree,  and  the 
correction  of  that  condition  would  obviate  the  use  of 
glasses  in  many  cases.  I  am  well  aware  that  this  is  an 
extreme  and  radical  view  of  these  conditions,  but  I  am 
giving  my  own  views  and  opinions  only. 

To  return  then  to  my  first  proposition,  as  to  the 
necessity  for  an  operation  on  these  straight  muscles,  we 


134 


STRABISMUS. 


have  two  conditions  which  are  to  be  considered :  First, 
is  there  a  want  of  balance  in  the  relative  power  of  these 
antagonistic  muscles  ?  Second,  can  the  patient  be 
relieved  by  any  other  means  than  an  operation  ?  To 
answer  these  questions  we  have  first  to  determine  what 
is  the  balance  of  power  in  these  muscles  ?  I  have 
demonstrated  that  the  normal  position  of  the  eyes  was 
one  in  which  both  eyes  will  be  directed  straight  forward 
to  a  point  about  fifteen  degrees  below  the  horizon  and 
with  the  look  in  infinity.  In  this  position  I  consider  the 
normal  eyes  in  a  state  of  rest.  Placing  the  eyeballs  in 
this  position  we  will  find  that  they  may  be  moved,  in  any 
possible  direction,  by  either  the  single  or  combined 
action  of  the  straight  muscles  ;  that  they  can  be  con- 
verged by  the  action  of  the  interni ;  that  they  can  be 
diverged  by  the' action  of  the  externi,  when  assisted  by 
artificial  means,  and  that  the  use  and  purposes  of  daily 
life  require  the  eyeballs  to  turn  downward  much  more 
than  upward. 

This  being  the  natural  action  of  these  straight  muscles, 
we  can  readily  understand  that  though  they  can  be 
antagonistic  to  each  other,  yet  the  requirements  of  life 
and  work  are  such  that  one  muscle  must  needs  be 
stronger  than  the  other,  at  the  same  time  the  eyeballs 
will  be  held  in  their  proper  positions  by  that  exquisite 
retinal  function,  the  guiding  sensation  or  fusion  power, 
which  alone  pertains  to  the  eye.  Then  if  it  is  necessary 
that  one  set  of  muscles  should  be  stronger  than  another 
and  considering  the  necessities  of  sight,  near  and  far,  we 
can  see  that  the  preponderance  of  power  must  exist  in 
the  interni ;  that  we  should  find  the  next  in  power  to  be 
the  externi ;  then  the  inferior,  and  lastly  the  superior, 
according  to  the  relative  need  of  action  by  these  respec- 
tive muscles. 

The  question  has  been  raised,  and  I   am  sorry  to  say 


INDICA  TIONS  FOR  AN  OPERA  TION.  \  3  5 

often  quoted,  that  the  prism  test  will  not  give  us  the  true 
power  of  the  muscles,  because  while  testing  one  eye 
there  will  be  a  corresponding  action  of  the  muscles  of 
the  other  eye  ;  as  if,  while  we  are  testing  one  internus 
with  the  prism  base  out,  the  externus  of  the  other  eye 
will  contract  at  the  same  time  to  overcome  the  supposed 
stimulation  of  both  interni  by  the  action  of  the  prism. 
In  some  of  my  cases  I  have  received  answers  from  my 
patients  that  would  indicate  some  unusual  action  of  the 
muscles  of  the  other  eye,  as  they  describe  the  position  of 
the  lights  when  diplopia  is  produced  by  prisms,  but  these 
cases  are  only  "  exceptions  to  the  rule,"  and  these  seem- 
ing contradictions  are  not  confirmed  by  the  other 
objective  tests.  As  a  rule  the  uncovered  eye  does  not 
move  from  the  first  position  and  this  I  have  proved  very 
frequently,  in  my  office,  with  the  assistance  of  an  intelli- 
gent patient.  I  proceed  as  follows :  By  placing  the 
prism  with  the  base  outward  over  one  eye  until  the 
patient  sees  the  two  images  of  the  light,  I  then  place 
Snellen's  test-card  behind  the  candle  and  have  the  patient 
read  the  letters  as  seen  by  each  eye.  I  find  that  the 
image  seen  by  the  uncovered  eye  will  be  clear  and  the 
letters  that  can  be  read  will  be  equal  to  20/15.  This 
shows  that  the  image  formed  by  this  eye  must  be  on  the 
macula,  as  the  slightest  deviation  from  this  region  will 
reduce  the  visual  power.  The  image  seen  by  the  prism- 
covered  eye  will  be  very  much  reduced  in  visual  acuity 
as  now  the  image  must  be  formed  on  the  peripheral  parts 
of  the  retina,  as  the  eye  is  turned  in  under  the  stimu- 
lation of  the  guiding  sensation.  We  have  no  evidence 
of  any  innervation  of  the  muscles  of  the  other  eye, 
except  the  occasional  cases  I  have  mentioned  above, 
but  as  the  action  of  one  eye  may  be  perfectly  in- 
dependent of  the  other  then,  as  a  rule,  the  eye 
will  not  move  from  the  first  position  except  under  the 


STRABISMUS. 

stimulation  of  the  fusion  power  when  an  image  falls  on 
the  peripheral  parts  of  the  retina. 

Now  we  make  our  crucial  test  for  the  relative  power  of 
these  straight  muscles  by  placing  prisms  in  the  trial  frames 
before  the  eyes,  with  the  bases  first  inward,  then  out- 
ward, then  upward,  and,  lastly,  downward,  over  each  eye 
separately.  This  process  is  continued  by  employing 
stronger  prisms  each  time,  as  long  as  the  eyes  will  blend 
the  images  of  the  candle  or  other  test  object  and  the 
strongest  prism  that  can  be  used  in  this  way  over  each 
muscle  after  several  trials  will  represent  or  indicate  the 
muscular  power  of  the  eye  to  turn  in  a  certain  direction 
in  the  field  of  fusion. 

Now,  in  reference  to  the  manner  of  employing  this 
test,  we  first  ascertain  the  power  of  the  externi,  for  I  con- 
sider the  abduction  power  of  this  muscle  to  be,  as  a  rule, 
constant..  We  next  test  the  interni,  and  here  we  should 
proceed  very  carefully,  as  this  muscle  may  respond  to  our 
test,  and  by  repeated  trials  we  find  an  increase  in  power. 
To  guard  against  this  we  should  continue  the  trial  on 
alternate  days  until  there  is  no  improvement.  Some  will 
rapidly  respond,  while  others  will  remain  the  same  as  at 
first.  Recording  these  results,  we  then  proceed  to  find 
the  power  of  the  inferior,  and,  lastly,  the  superior.  What 
should  be  the  result  of  this  examination  ? 

Again,  referring  to  my  previous  articles,  we  should 
find  a  certain  proportionate  balance,  as  follows  :  First, 
in  reference  to  the  lateral  moving  muscles,  if  we  take  the 
power  of  the  externi  as  one,  then  we  should  find  that  of 
the  interni  to  be  two  or  three  times  stronger,  or  as  one  to 
two  or  three.  As,  for  example,  if  the  externi  can  overcome 
the  deviation  of  a  prism  of  6°,  then  the  interni  should 
overcome  one  of  12°  to  20° ;  likewise,  in  testing  the  power 
to  move  the  eye  up  and  down,  we  should  find  the  inferior 
stronger  than  the  superior.  I  am  convinced  it  makes  no 


IXDICA  TIOXS  FOR  AN  OPERA  TION 


137 


difference  what  may  be  the  power  of  any  individual 
muscle,  provided  we  find  the  above-mentioned  propor- 
tion, namely,  the  interni  stronger  than  the  externi,  and 
the  inferior  than  the  superior. 

I  can  hardly  agree  with  Stevens  that  the  externi  must 
overcome  a  prism  of  8°  to  be  of  normal  power,  as  that 
would  indicate  the  interni  should  evercome  a  prism  of 
30°  degrees.  I  do  not  think  it  is  important  what  may  be 
the  abducting  power,  provided  the  adducting  power  shall 
be  found  to  be  much  greater.  I  make  it  a  rule  to  test 
the  lateral  moving  muscles  in  all  my  cases,  and  have  yet 
to  record  a  case  where  I  have  found  the  power  of  these 
muscles  anywhere  near  that  suggested  by  Stevens.  I 
frequently  find  the  externi  as  high  as  8°,  sometimes  15°, 
but  the  interni  seldom  goes  above  30°.  Having  com- 
pleted our  test  with  the  prisms  and  noted  the  indications, 
we  now  proceed  to  examine  the  field  of  version  with  the 
tropometer.  If  this  indicates  the  same  imbalance  as  the 
fusion  test,  \ve  are  then  ready  to  decide  the  necessity 
and  the  method  of  our  operation. 

To  read  the  indications  rightly  we  must  accept  a  normal 
rotation  of  the  eyes  in  the  fields  of  fusion  and  of  fixation, 
as  set  forth  in  previous  lectures  and  then  to  compare  the 
results  of  our  examination  of  the  patient's  ocular  balance 
with  that  of  the  normal  standard,  being  careful  to  particu- 
larly note  the  relation  that  one  rotation  bears  to  another 
in  regard  to  the  proportion. 

In  heterophoria,  what  are  the  indications  and  what  is 
the  operative  procedure  ?  What  will  our  examination 
indicate  ?  We  may  first  decide  the  condition  of  hetero- 
phoria by  the  rod  test  or  the  phorometer,  by  which 
we  can  only  decide  the  presence  of  esophoria,  exophoria, 
and  hyperphoria,  and  the  degree.  The  next  step  is  the 
prism  test,  which  will  indicate  the  location  of  the  weaker 
muscle  or  muscles,  in  all  cases,  as  we  compare  the 


138  STRABISMUS. 

results  with  the  normal  balance  and  the  relation  one  to 
the  other.  We  then  proceed  to  the  examination  with 
the  tropometer,  also  comparing  this  with  the  normal 
rotation.  This  examination  should  confirm  in  every 
way  the  examination  with  the  prisms  and  it  will  also  indi- 
cate if  we  have  the  conditions  of  anaphoria,  kataphoria, 
or  a  tendency  to  turn  to  the  right  or  left.  All  these 
examinations  being  carefully  and  repeatedly  made  we 
are  ready  to  select  the  best  operative  procedure. 

Now  we  will  meet  cases,  as  we  study  the  results  of  our 
examinations,  that  show  an  excess  of  power;  in  other 
words,  some  of  the  muscles  seem  to  be  too  strong.  This 
condition  has  been  called  an  "  excess  of  convergence,"  or 
-"excess  of  divergence,"  as  the  case  may  be.  If  this 
increase  or  excess  is  shown  to  be  much  more  than  the 
normal  rotation  —  it  is  frequently  so  in  exophoria — we  may 
decide  on  a  partial  or  a  complete  tenotomy,  according  to 
the  effect  desired,  as  the  first  operative  procedure  before 
we  attempt  to  increase  the  rotational  power  by  a  shorten- 
ing. But  excess  must  imply  deficiency  somewhere,  and 
when  we  endeavor  to  estimate  the  effect  of  an  operation 
we  must  bear  in  mind  that  the  result  of  a  partial  tenot- 
omy will  be  obviously  less  than  a  complete  tenotomy  if 
we  wish  to  weaken  the  rotation  of  an  eye,  and  that,  if 
a  strengthening  operation  is  indicated,  the  shortening  of 
the  muscle  will  give  us  all  the  desired  effect,  as  if  needed 
it  may  be  performed  on  both  eyes. 

A  careful  analysis  of  the  results  of  these  examinations, 
in  almost  every  case,  will  show  some  weakness  of  one  or 
more  of  the  straight  muscles  of  the  eyes,  and  if  so,  the 
indications  become  clear,  namely,  to  improve  and  to 
strengthen  the  function  of  those  weak  muscles.  I  know 
of  no  operation  that  will  accomplish  this  object  so 
"  quickly,  safely,  and  judiciously  "  as  that  of  the  shorten- 
ing process  to  be  described.  This  operation  was  devised, 


INDICA  TIONS  FOR  AN  OPERA  TION. 


139 


practised,  and  demonstrated  by  myself  before  I  had  any 
knowledge  that  others  had  been  working  in  the  same  lines, 
but  after  I  had  performed  a  number  of  these  operations 
and  published  the  results  in  the  Post-Graduate  Journal, 
July,  1895,  I  was  informed  by  Dr.  G.  C.  Savage  that  he 
had  described  a  similar  procedure  in  the  Ophthalmic 
Record,  March,  1893.  In  this  editorial  Savage  describes 
his  operation  as  follows :  He  uses  two  needles  on  a  silk 
suture,  and  these  needles  are  passed,  one  above  and  the 
other  below,  through  the  muscular  tissue  to  the  tendon 
and  then  tied.  In  the  details  of  the  operation,  as  I  have 
always  performed  it,  I  use  the  twin  hooks  to  hold  the 
muscles  and  to  expose  its  muscular  tissue.  The  tendon 
and  muscular  tissue  is  completely  dissected,  and  the  use 
and  the  method  of  the  introduction  of  the  catgut  suture 
obviates  the  necessity  of  a  second  operation  for  the 
removal  of  the  suture.  By  this  operation,  when  the  mus- 
cle is  innervated  by  the  stimulation  of  the  guiding  sensa- 
tion, the  shortening  of  the  length  of  the  muscle  must 
cause  it  to  have  an  increased  power  to  turn  the  eye.  The 
operation  is  fully  explained,  and  as  it  has  been  repeatedly 
performed  by  myself  and  others  it  may  be  said  to  have 
passed  the  experimental  stage. 

The  Indications  in  Fixed  Squint.  For  the  past  year, 
with  the  assistance  and  suggestions  of  Dr.  E.  M.  Alger,  I 
have  been  noting  the  effect  of  different  operations  on  the 
eyes  in  squint,  that  is  to  say,  what  effect  will  a  certain 
operation  have  on  the  rotation  of  an  eyeball  when  per- 
formed. It  has  been  my  misfortune  to  see  a  very  few 
cases  that  had  been  operated  upon  by  myself  for  conver- 
gent squint  some  years  ago.  They  came  back  to  me 
with  a  divergent  squint  coming  on  some  time  after  the 
first  operation.  It  is  to  prevent  this  result  that  I  have 
endeavored  to  perform  my  operations.  At  the  present 
time  I  think  that  the  following  conclusions  will  be  the 


140 


STRABISMUS. 


safest  and  best  method  of  procedure  to  obtain  a  per- 
manent effect  and  in  many  cases,  possibly,  binocular 
vision.  It  will  be  noted  that  I  have  divided  my  cases  of 
fixed  squint  into  two  classes,  and  in  each  class  I  think  we 
should  adopt  a  somewhat  different  procedure.  In  squint 
of  the  first  class,  with  amblyopia,  I  operate  on  the  ambly- 
opic  eye  only  in  this  way  :  Place  the  catgut  suture  in 
position  (see  Operations)  in  the  weak  externus  (or  inter- 
nus,  if  divergent  squint),  and  before  this  suture  is  tied  do 
a  complete  tenotomy  on  the  opposing  muscle.  Now  tie 
the  suture,  drawing  forward  the  muscular  tissue  until  the 
eye  is  in  its  proper  position.  It  is  always  best  to  do  this 
operation  under  cocaine,  as  we  then  can  see  the  effect  of 
-the  procedure  as  the  operation  is  completed.  In  divergent 
squint  a  slight  overcorrection  will  be  advisable  if  it  can 
be  obtained.  I  have  adopted  the  above  procedure  for 
several  years  and  have  failed  to  see  the  case  in  which  I 
was  not  satisfied  with  the  result.  In  these  cases  I  can 
only  expect  to  get  a  good  cosmetic  effect  as  I  have  no 
confidence  in  the  restoration  of  vision  in  a  congenitally 
amblyopic  eye,  and  consequently  do  not  make  any  effort 
to  get  binocular  vision  in  the  after  treatment  of  these 
cases.  The  refraction  should  always  be  corrected. 

In  the  second  class  of  cases,  those  with  good  vision  in 
each  eye  or  only  amblyopia  ex-anopsia,  I  now  prefer  to 
do  the  shortening  operation  on  both  externi,  in  conver- 
gent squint,  on  both  interni,  in  divergent  squint,  and 
then  to  perform  a  very  careful  tenotomy  on  the  opposing 
muscle  or  muscles,  if  needed,  not  lacerating  the  capsule 
of  Tenon  mote  than  is  absolutely  necessary  to  put  the 
eyes  in  the  first  position.  This  procedure,  followed  by 
suitable  glasses  to  correct  any  refractive  error,  suitable 
exercise  with  the  prisms,  and  other  methods,  should  cor- 
rect the  squint,  and,  in  many  cases,  result  in  that  much  to 
be  desired  condition,  binocular  vision  and  fixation,  the  ideal 


INDICA  TIONS  FOR  AN  OPERA  TION. 


141 


eyes.  I  am  well  satisfied  that  in  all  cases  of  vertical 
squint,  hyperphoria,  the  shortening  operation  is  always 
indicated. 

I  would  refer  the  reader  to  the  chapter  on  Illustrative 
Cases  for  the  practical  application  of  all  these  indications, 
where  we  have  the  results  of  the  examination  before  the 
operation,  the  operations  performed  and  the  attainment 
of  the  normal  balance  as  the  final  result.  Hence,  we 
always  have  the  following  object  in  view,  in  the  treatment 
of  all  cases  of  squint,  either  fixed  or  latent.  In  hetero- 
phoria,  to  attain  the  normal  balance  of  duction  and  ver- 
sion, and  in  heterotropia,  fixation,  and  binocular  vision. 


CHAPTER  X. 

OPERATIONS. 

"  The  only  type  of  heterophoric  asthenopia  that  can  legitimately 
admit  of  operative  interference  is  the  idiopathic."  —  "  The  fault  must 
be  located  in  the  part  upon  which  the  operation  is  done."  —  "The 
fault  should  not  be  one  of  improper  innervation  from  a  central  or 
peripheral  cause."  —  "It  is  a  local,  physical  deformity,  with  an  imper- 
fect and  disturbing  physiological  result." — "Anatomic  readjustment 
of  improperly  placed  muscular  tissue  and  tendon  is  the  only  legiti- 
mate result." — C.  A.  Oliver,  M.  D.,  in  Norris  and  Oliver,  Vol.  IV.,  p. 
-465. 

WHEN  we  come  to  consider  the  operations  on  the  eye- 
ball for  the  correction  of  either  latent  or  fixed  squint, 
there  are  but  few  anatomical  points  to  remember.  Of 
these,  the  most  important,  and  one  that  may  possess  some 
complications  in  the  course  of  our  operation,  is  that  of  the 
insertion  of  the  tendons  of  the  ocular  muscles  into  the 
sclera.  In  my  description  of  the  movements  of  the  eye  I 
have  stated  the  positions  in  which  these  insertions  of  the 
tendons  will  be  found.  They  form  somewhat  of  a  spiral, 
if  we  take  the  insertion  of  the  internus  as  being  nearest 
to  the  limbus  of  the  cornea.  Then  somewhat  farther 
away  we  will  find  the  insertion  of  the  inferior,  and  that  of 
the  superior  placed  much  farther  from  the  edge  of  the 
cornea  than  all  the  others.  These  insertions  become  very 
important  as  £hey  bear  a  very  positive  relation  to  an  oper- 
ation and  form  fixed  points  that  should  be  fully  appreciated, 
even  before  the  conjunctiva  is  cut,  that  they  may  be  quickly 
found  when  the  incisions  are  made. 

The  size  of  the  tendon  should  also  be  remembered,  as 
we  will  find  the  tendon  of  the  internus  much  larger  than 
that  of  the  other  muscles.  The  tendon  of  the  externus 


OPERATION'S.  143 

may  be  found  very  loose,  as  it  does  not  seem  to  grasp  the 
eyeball  in  the  same  manner  as  other  muscles. 

Asepsis.  In  reference  to  this  subject,  I  think  too  much 
stress  has  been  placed  upon  it  in  reference  to  operations 
on  the  ocular  muscles.  The  field  of  operation  certainly 
must  be  in  an  almost  aseptic  condition  all  the  time,  unless 
there  is  some  pre-existing  disease  of  the  conjunctiva,  and 
during  the  healing  process  we  have  the  wound  constantly 
bathed  in  the  secretions  of  the  lachrymal  gland  as  they 
pass  over  the  conjunctival  sac  to  the  puncta.  Hence  the 
only  asepsis  that  we  need  is  perfect  cleanliness  of  the  eyes 
and  the  hands  of  the  operator.  Thorough  washing  of  the 
hands  and  sterilization  of  the  instruments  is  the  first 
requisite,  and  just  before  the  operation  the  lids  and  con- 
junctival sac  should  be  washed  out  with  a  solution  of 
boracic  acid  or  boiled  water.  With  these  preparations  we 
are  ready  for  our  operation. 

In  the  description  of  these  operations  I  shall  give  them 
as  they  are  performed  by  myself,  while  to  those  who  may 
wish  to  follow  other  methods  or  other  operations,  I 
would  refer  to  the  writers  on  this  subject,  particularly  to 
the  article  by  Knapp,  in  Norris  and  Oliver  s  System,  Vol. 
III.  In  these  operations  I  describe  those  of  cutting  the 
tendons  first,  though,  as  I  study  the  effects  of  the  opera- 
tions on  the  eyeball  for  any  of  the  degrees  of  squint,  I 
should  put  that  of  strengthening  the  muscle  in  the  first 
place,  for  the  reason  that  I  believe  the  essential  cause  of 
all  squint  is  a  weakness  of  some  one  or  more  of  the  mus- 
cles of  the  eyeball.  If  that  proposition  be  true,  then  it 
seems  reasonable  that  our  first  operative  procedure  should 
be  a  strengthening  one,  to  be  followed  by  a  weakening  or 
tenotomy  of  the  opposing  muscle,  if  needed.  In  all  my 
operations  on  the  muscles  of  the  eye  I  prefer  the  local  use  of 
cocaine  in  4  per  cent  solution, —  a  few  drops  of  this  placed 
in  the  conjunctival  sac  before  the  operation  being  all  that  is 


144 


STRABISMUS. 


SMALL   STRAIGHT   SCISSORS. 


FIXATION   FORCEPS. 


SMALL  CURVED  SCISSORS. 


CAPSULE  —  STERILIZED   CATGUT 


SMALL   AND    LARGE    STRABISMUS   HOOKS. 


NEEDLE    HOLDER. 


INSTRUMENTS   NEEDED  FOR  THESE  OPERATIONS. 


OPERATIONS.  145 

needed  to  make  the  operation  almost  painless.  I  have 
never  experienced  any  ill  effect  from  the  use  of  this  drug. 
Before  the  operation  I  put  one  drop  Sol.  Adrenalin  Chlor. 
i  :  1000,  on  the  conjunctiva.  If  an  anaesthetic  is  desired 
for  these  operations,  I  prefer  the  nitrous  oxide,  except  with 
children,  when  chloroform  or  ether  may  be  used. 

Partial  Tenotomy.  The  object  of  this  operation,  it 
seems  to  me,  is  to  produce  a  very  slight  effect  on  the  rota- 
tion of  the  eye.  We  proceed  as  follows : 

The  eye  being  prepared  as  above,  the  speculum  is  intro- 
duced first  under  the  upper  lid,  then  the  lower,  and  the 
eyelids  separated  only  sufficiently  to  render  the  field  of 
operation  clear.  The  conjunctiva  is  now  grasped  with  a 
pair  of  fixation  forceps,  exactly  over  the  insertion  of  the 
tendon,  raised  up  slightly  from  the  sclera,  and  a  small 
incision  made.  One  blade  of  the  scissors  is  then  carried 
beneath  the  conjunctiva  and  the  incision  is  enlarged  in  the 
direction  of  the  muscle,  horizontally  if  we  are  operating  on 
the  lateral  muscles.  The  capsule  of  the  tendon  is  now 
opened  by  a  small  incision  into  Tenon's  capsule,  and  a 
small  strabismus  hook  is  passed  beneath  the  tendon. 
Raising  the  tendon  slightly  on  the  hook,  I  now  cut  the  fibres 
on  both  sides,  as  the  upper  and  lower  ones  on  the  internus, 
by  a  number  of  small  cuts,  until  the  center  of  the  tendon  is 
reached.  At  this  point  I  leave  a  small  portion,  about  the 
size  of  a  large  thread  attached,  to  the  sclera.  The  hook 
is  now  removed,  the  conjunctiva  smoothed  back  into  its 
place,  the  speculum  removed,  and  the  eye  washed  with  a 
solution  of  boracic  acid. 

Complete  Tenotomy.  In  this  procedure  we  obtain  a 
greater  effect  on  the  motility  of  the  eye,  according  to  the 
extent  of  our  separation  of  the  capsule  from  the  sclera. 
The  steps  of  the  operation  are  the  same  as  those  for  a 
partial  tenotomy,  but  the  tendon  is  cut  completely  from 
the  sclera,  always  commencing  at  the  point  of  the  hook 


1 46  S  TRABISMUS. 

so  as  to  cut  all  the  fibres.  If  a  decided  effect  is  wanted, 
the  expansions  of  the  tendon  are  taken  up  on  the  hook, 
both  above  and  below,  on  the  lateral  muscles,  and  com- 
pletely severed  from  the  sclera. 

These  operations  require  very  little  after  treatment. 
For  the  first  twenty-four  hours,  cold  applications  are  very 
grateful,  and  after  that  time  a  lotion  of  boracic  acid  is  all 

o 

that  is  needed.  The  effect,  which  will  be  shown  when 
the  eyes  are  tested,  is  about  5  to  15  degrees  in  hetero- 
phoria.  In  squint,  a  decided  change  in  the  position  of  the 
visual  line.  This  must  vary  according  to  the  fusion  force 
of  the  eye  and  the  degree  of  the  squint. 

SHORTENING    OF    THE    OCULAR    MUSCLES. 

The  operation  for  advancement  of  the  ocular  muscles 
has  been  in  use  by  ophthalmic  surgeons  for  many  years, 
and  has  been  changed  and  modified  by  many,  but  as  it  is 
performed  at  the  present  time  it  is  a  delicate  and  exten- 
sive operation  in  which  an  assistant  is  required.  Further- 
more, the  subsequent  removal  of  the  sutures  is  almost  a 
second  operation.  I  believe  that  owing  to  these  condi- 
tions the  operation  is  seldom  performed  unless  it  is  abso- 
lutely necessary,  as  in  cases  of  extreme  divergent  squint, 
paresis  or  paralysis  of  the  ocular  muscles.  For  the  past 
seven  years  I  have  successfully  attempted  a  different 
method  to  attain  the  same  object,  provided  the  result 
desired  is  not  too  great.  I  think  that  I  have  succeeded 
in  devising  a  method  of  shortening  the  ocular  muscles 
that  is  easy  to  perform,  that  does  not  require  an  assist- 
ant, or  the  removal  of  the  suture,  and  that,  moreover, 
produces  an  entirely  satisfactory  result. 

I  will  describe  the  procedure  and  also  the  instrument 
that  I  find  very  useful  and  of  great  assistance  while  pass- 
ing the  suture.  This  instrument  was  made  for  me  by 
Mr.  E.  B.  Meyrowitz  of  this  city. 


OPERATIONS.  147 

When  the  eye  is  prepared  for  the  operation  and  the 
specula  inserted,  the  conjunctiva  is  grasped,  not  over  the 
center  of  the  tendon  as  in  tenotomy,  but  over  the  lower  or 
upper  part  of  the  insertion,  raised  up,  and  a  small  opening 
made.  From  this  point  I  make  a  lateral  incision,  and  then 
a  vertical  one  forming  an  L.  This  is  raised  up  very  care- 
fully and  dissected  from  the  sub-conjunctival  tissue  and 
laid  back.  We  now  grasp  the  capsule  with  the  forceps 
at  the  lower  part  of  the  insertion  of  the  tendon,  a  small 
opening  is  again  made,  and  the  hook  passed  beneath  until 
its  point  protrudes  on  the  opposite  side.  Another  hook 
is  now  passed  beneath  the  tendon  in  an  opposite  direction. 
These  two  hooks  are  now  drawn  apart,  in  this  way  expos- 
ing the  tendon  and  muscle. 


EXPOSURE  OF  THE  MUSCLE,  AFTER  HANSEL  AND  REBER. 

The  twin  strabismus  hooks  are  now  inserted  under  the 
muscle  between  the  other  hooks,  which  are  then  removed 
and  the  twin  hooks  allowed  to  separate  from  the  pressure 
of  the  spring.  If  they  do  not  separate  sufficiently,  or  as 
far  as  I  wish  to  shorten  the  muscle — and  I  judge  this 
procedure  by  the  indications,  as  to  the  amount  of  short- 
ening necessary — I  then  place  the  blades  of  a  pair  of 
scissors  between  the  hooks  and  open  them  forcibly  until  I 
get  the  desired  result. 


148 


STRABISMUS. 


TWIN    STRABISMUS   HOOKS. 


This  instrument  will  stay  in  position  without  holding, 
and  we  are  now  ready  for  the  insertion  of  the  catgut 
suture.  This  is  always  used  in  the  operation,  as  a  thread 
requires  almost  a  second  operation  to  remove  it.  I  use 


CATGUT  SUTURE  IN  CAPSULE. 


a  very  small  Hagedorn  needle  with  a  very  large  eye,  so 
that  it  can  be  easily  threaded.  The  catgut  —  sizes  o  oroo 
—  is  used  from  a  glass  capsule  holding  sufficient  for  one 
operation. 


DIAGRAM  SF  NEEDLES,  SUTURE  AND  HOOKS 
IN  POSITION. 

Armed  witlj  the  needle  and  suture,  we  are  now  ready 
to  pass  it  in  the  following  manner :  using  the  insertion  of 
the  tendon  as  a  fixed  point,  the  needle  is  passed  through 
its  upper  or  lower  edge,  including  part  of  the  sclera  if 
possible,  and  going  beneath  the  blade  of  the  twin-hooks. 
We  now  carry  the  needle  backward  beneath  the  other 
hook  and  pass  it  through  the  muscular  part  from  within 


OPERATIONS.  149 

outward.  Carrying  the  suture  now  across  the  muscle,  we 
again  pass  the  needle  through  the  muscular  part  at  a  point 
opposite  the  last  puncture,  going  from  without  inward. 
The  suture  is  drawn  down  close  to  the  muscle  and  the 
needle  is  now  carried  back  to  the  tendon,  passed  beneath 
it  at  a  point  opposite  to  the  first  insertion,  then  through 
the  tendon,  close  to  the  sclera.  As  the  suture  is  drawn 
tight,  it  will  now  present  the  form  of  a  parallelogram, 
(see  diagram.) 

The  twin  hooks  are  now  removed  and  the  two  ends  of 
the  suture  are  carefully  and  evenly  tied  with  a  surgeon's 
knot  over  our  fixed  point,  the  insertion  of  the  tendon. 
As  it  is  drawn  tight,  we  see  the  knuckle  or  tuck  of  the 
muscle  forming  as  the  muscular  tissue  is  drawn  forward. 
After  the  suture  is  securely  tied,  the  ends  are  cut  off  and 
the  flap  of  conjunctiva  is  drawn  back  into  place  over  the 
tuck  in  the  tendon,  then  the  specula  is  removed.  This 
flap  does  not  need  a  suture  to  keep  it  in  place,  unless  there 
should  be  some  decided  opening  of  the  wound,  when  it 
may  be  readily  closed  with  a  small  superficial  suture. 


DIAGRAM   OF   SUTURE   TIED,  SHOWING  TUCK, 
AFTER  HANSELL  AND  REBER. 


The  after  treatment  is  the  same  as  that  of  tenotomy, 
and  at  no  time  do  I  close  the  eye  with  a  bandage,  except 
in  an  office  operation,  and  then  only  when  they  are  going 


1 50  STRABISMUS. 

home.  I  prefer  this  open  treatment  after  the  operation 
because  it  seems  to  me  better  that  the  eyes  should  be 
used  as  the  healing  process  takes  place,  so  that  we  can 
keep  the  fusion  force  constantly  active.  The  results  of 
this  operation  will  be  found  to  show  about  10  to  15  de- 
grees correction  of  the  visual  line  in  squint  and  a  decided 
improvement  in  the  fields  of  version  and  fusion  in  hetero- 
phoria. 

I  would  state  that  I  was  the  first  to  use  the  catgut 
suture  to  take  a  tuck  in  these  muscles  and  allow  it  to  be 
absorbed,  therefore  requiring  no  further  interference  with 
the  eye.  I  have  found  this  method  very  useful  in  con- 
vergent squint,  in  divergent  squint,  in  paralysis,  and  par- 
ticularly in  insufficiency  of  the  ocular  muscles,  where  the 
indications  are  to  strengthen  the  weaker  muscles  instead 
of,  as  in  the  old  method,  weakening  the  stronger  muscles 
by  a  partial  or  complete  tenotomy.  Savage  published 
the  first  account  of  this  method  of  shortening  an  ocular 
muscle  in  1 893  —  using  a  black  silk  suture  to  form  the  tuck. 
I  give  the  records  of  twenty  operations  performed  by 
this  method,  and  in  all,  the  results,  for  the  relief  of  the 
symptoms  or  the  correction  of  the  squint,  have  been  very 
gratifying.  In  only  one  case  has  there  been  any  failure 
of  rapid  and  complete  healing  of  the  tissues  and  in  this 
case  I  had  a  small  stitch  abscess  due  to  a  fault  in  the  cat- 
gut used.  The  following  twenty  operations  will  illustrate 
the  conditions  in  which  I  think  the  use  of  the  suture  is 
indicated  : 

For  convergent  and  divergent  squint         .        .12  cases 

For  paresis  or  paralysis i  case 

For  heterophoria,  all  forms  7  cases 

Total     ........      20  cases 

These  cases  are  not  included  in  those  of  special  deviations. 
CASE  I.  —  Paresis  of  the  Left  Externus.     F.  A.  F.,  age  30.  Homon- 
ymous    Diplopia.     Operation:  Shortening  with  catgut    suture,   1894 
Result,  complete  relief  of  the  diplopia. 


OPERA  TIONS.  1 5  I 

CASE  II.  —  Weakness  of  the  Externi,  Esophoria.  Mrs.  H.  T.  N.,  age 
38.  Pain  in  the  head  extending  down  the  spine  ;  she  cannot  use  the 
eyes  ;  when  reading  pain  is  much  worse.  Refraction  examined  under 
atropine  and  glasses  ordered.  After  one  month's  trial  they  do  not 
relieve  the  pain.  Repeated  examination  shows  a  want  of  balance  in 
the  eyes;  Add.  20°;  abd.  o°.  Esophoria  =  6°.  Jan.,  1896,  —  catgut 
suture  in  left  externus.  Result,  Add.  20°,  abd.  6°.  She  was  advised 
by  another  oculist  not  to  have  an  operation.  1903.  I  have  met  this 
lady  and  she  states  that  she  has  had  no  further  trouble  with  the  eyes. 

CASE  III.  —  E.  A.  W.,  age  23.  Sent  to  me  by  Dr.  Carter.  Head- 
aches frontal,  extending  backward.  Manifest  hyperopia,  +  .50  D. 
with  V.  =  20/20,  each;  Add.  16°  ;  abd.  o°.  May,  1896,  catgut  suture 
in  the  left  externus.  Result,  cessation  of  the  headaches  and  now 
Add.  16 °  ;  abd.  4° .  It  was  in  this  case  that  the  slight  infection  of  the 
wound  occurred. 

CASE  IV.  —  Weakness  of  the  Interni,  Exophoria.  Miss  A.  S., 
aged  30.  Headaches,  frontal  and  occipital.  Refraction,  compound 
myopic  astigmatism  axes  toward  the  temples,  corrected  with 
glasses,  but  after  four  months'  trial  no  relief.  Has  crossed  diplopia  ; 
and  by  prism  test,  Add.  2° ;  abd.  10°.  In  1894-95,  I  did  the  shorten- 
ing operation  on  both  interni  and  a  partial  tenotomy  on  both  externi. 
Result,  patient  was  much  better.  Add.  16°  ;  abd.  8°,  but  she  was 
not  completely  relieved  from  the  asthenopic  symptoms.  It  will  be 
noted  in  this  case,  that  the  power  of  the  externi,  in  the  field  of 
fusion  is  still  too  great. 

CASE  V.  —  Mr.  C.  J.  S.,  aged  32.  Has  not  used  the  eyes  for  work- 
ing or  for  reading  during  the  past  three  years  ;  he  is  neurasthenic  ; 
complains  of  drawing  sensation  in  the  back  of  the  head  and  neck. 
This  is  a  common  symptom  in  these  cases  of  heterophoria.  This 
man  has  myopic  astigmatism  that  had  been  fully  corrected  by  glasses 
but  they  do  not  give  him  any  relief.  Crossed  diplopia  ;  by  prism  test 
4°,  and  at  times  has  double  vision.  Add.  12°,  changing  by  repeated 
trials  ;  abd.  10°  ;  Nov.  i,  1895,  catgut  suture  in  right  internus. 
Two  weeks  after,  Add.  30°  ;  abd.  8°.  Two  months  after  operation 
reports  by  letter  that  he  is  back  at  work,  bookkeeping,  and  feels 
better  than  he  has  for  several  years. 

CASE  VI.  —  Miss  S.  J.,  aged  25  years.  Is  very  dizzy,  and  has  had1 
double  vision  for  past  six  months.  V.  =  f£,  —  Hm.  50  D.,  Add  3°  ; 
Abd.  5°.  Catgut  suture  in  right  internus.  Two  months  after, 
all  symptoms  disappeared  and  Add.  12°  ;  Abd.  5°.  To  use  +.  50  D. 
glass  for  reading.  I  saw  this  lady  fifteen  months  after  the  opera- 


152  STRABISMUS. 

tion,  and  on   examination  the  lateral   balance  of   the   muscles   was 
Add.  16°  ;  Abd.  5°. 

CASE  VII. —  Mrs.  G.  H.,  aged  49  years.  Headaches,  frontal,  and 
has  dizzy  spells.  V.  =  20  _  W-  +  x  D.,  cyl.  ax.  90°  =  ?a  — .  Add. 
6°  ;  Abd.  6°.  Catgut  suture  in  left  internus.  Three  months  after, 
reports  much  better.  Add.  12°  ;  Abd.  6°. 

Convergent  Concomitant  Squint,  first  class,  seven  cases. 

CASE  VIII. —W.  G.,  aged  20  years.  R.  V.  =  fa  + ;  L.  V.  = 
fingers  at  two  feet.  December,  1895.  Tenotomy  of  left  internus. 
Immediate  result  good,  but  squint  returned.  January,  1896.  Catgut 
suture  in  left  externus.  Two  months  after,  perfect  cosmetic  effect ; 
no  change  in  vision. 

CASE  IX.—  D.  B.,  aged  17  years.  R.  V.  =  f&  ;  L.  V.  =  fingers  at 
ten  feet.  Has  compound  hyperopic  astigmatism.  September,  1895. 
Catgut  suture  in  left  externus  and  tenotomy  of  left  internus.  Per- 
fect cosmetic  result.  Ordered  +  2  D.,  cyl.  ax.  90°. 

CASE  X,  —  S.  D.,  aged  5  years;  glasses  for  two  years,  correcting 
refraction  of  +  i  D.  in  each  eye,  but  no  improvement  in  squint. 
Operation  at  hospital  under  ether.  May,  1896. — Catgut  suture  in 
left  externus  and  tenotomy  of  left  internus.  Perfect  cosmetic 
result. 

CASE  XI. —Mrs.  L.  B.,  aged  31  years,  Liberty,  N.  Y.  R.  V.  = 
,fo  ;  L.  V.  =  §g  w.  +  ^  3  +  ^  cyl.  ax.  180°  =  |g.  Put  catgut 
suture  in  right  externus  with  perfect  cosmetic  result. 

CASE  XII. — E.  A.  P.,  aged  8  years.  This  boy  has  slight  nystag- 
mus in  both  eyes  with  the  squint.  R.  V.  =  ffa,  Hm.  2  D.  ;  L.  V 
(?)  ;  oph.  shows  Hy.  6  D.  May,  1895.  Under  ether  and  assisted  by 
Dr.  Coffin,  I  put  catgut  suture  in  left  externus  and  did  a  complete 
tenotomy  of  left  internus.  Four  months  after,  perfect  cosmetic 
result.  R.  V.  =  ^fa  ;  L.  V.  =  fingers  at  4  ft.  ;  no  nystagmus.  Eight 
months  after,  same  vision. 

CASE  XIII.— E.  W,,  aged  23  years.  R,  V.  =f§,  Hm.  i  D,  ;  L. 
V.  =5^0.  Hm.-3  D. ;  opthalmoscope  same  degree  of  hyperopia. 
March,  1895.  Catgut  suture  in  left  externus  and  tenotomy  of  both 
interni.  Perfect  cosmetic  result. 

CASE  XIV.  —  F.  L.,  aged  13  years.  This  young  girl  had  hysteri- 
cal amblyopia  associated  with  her  convergent  squint.  Refraction, 
compound  hyperopic  astigmatism.  R.  V.  =  shadows,  L.  V.  =  ^j. 
February,  1896.  Catgut  suture  in  left  externus  while  under  ether. 


OPERATIONS.  153 

One  month  after,  no  squint  and  vision  slowly  returning,  R.  V. 
counts  fingers,  L.  V.  =  2  J]. 

Divergent  Concomitant  Squint,  first  class,  two  cases. 

CASE  XV. —  S.  D.,  aged  15  years.  R.  V.  =  o2^  ;  L.  V.  =  f  g — ; 
can  fix  with  both  eyes  at  near  point,  but  at  distant  vision  right  eye 
turns  outward.  March,  1896,  Catgut  suture  in  right  internus. 
Has  hyperopic  astigmatism,  and  I  ordered  -f  .50  D.,  cyl.  ax.  90°  for 
each  eye.  Result  perfect. 

CASE  XVI, —  A.  C.,  aged  15  years.  Divergence  of  right  eye  since 
childhood.  R.  V.  =  5§o  '•>  L-  v-  =  fS-  Refraction  R.  =  compound 
myopic  astigmatism;  L,  =  Hm.  May,  1896,  Catgut  suture  in 
right  internus  and  tenotomy  of  the  externus.  Perfect  cosmetic. 

Convergent  Concomitant  Squint,  second  class,  three  cases. 

CASE  XVII.  —  G.  F.,  aged  7  years.  Alternating  squint.  Hypero- 
pia,  3  D.  Atropine  and  glasses  tried  for  three  months  ;  no  result. 
January,  1896.  Catgut  suture  in  the  left  externus  and  tenotomy 
of  the  internus.  Six  weeks  later  ordered  +  2.  D.  each  eye.  Result 
perfect. 

CASE  XVIII.  —  H.  H..  aged  13  years.  Right  eye  turns  inward- 
Esophoria,  or  slight  convergent  squint.  R.  E.  V.  =  20/200.  w.  —  4. 
D,  =  20/70.  ;  L.  E.  V.  =  20/70.  w,  — ,50  D.  =  20/40.  Under 
atropine  R,  E.  =  20/200,  w.  —  1.50  D.  =  20/70  ;  L.  V.  =  20/70, 
w.  —  50  o — -5°  cyl-  ax-  3°°  =  20/40  +.  These  glasses  do  not  cor 
rect  the  squint  or  change  it  in  any  way,  so  I  did  the  operation  of 
shortening  the  right  externus.  The  result  was  perfect, 

CASE  XIX.  —  D,  O.  C.,  aged  28.  Convergent  squint  since  child- 
hood, R,  V,  =  20/50,  w,  +  .50  cyl.  ax.  90°  =  20/40  ;  L.  V, 
=  20/20.  improved  w,  +  .50  cyl,  ax.  90°.  August,  1895.  I  did  a 
complete  tenotomy  of  the  right  internus  and  the  next  day  put  in 
the  catgut  suture  in  the  left  externus.  In  this  case  the  result  was 
excellent  as  we  had  binocular  vision. 

In  all  these  cases,  from  my  private  practice,  in  which 
the  suture  was  inserted  twenty  times,  the  relief  of  the 
muscular  asthenopia,  the  paresis  and  the  squint  has  been 
very  satisfactory.  In  the  asthenopic  cases  we  have  im- 
mediate relief  and  gradual  improvement ;  in  paresis  the 
diplopia  disappeared  and  in  squint  the  cosmetic  effect 
was  all  that  could  be  desired.  In  all  the  healing  was 


1 54  STRABISMUS. 

clean  and  rapid  with  only  a  slight  oedema  of  the  ocular 
conjunctiva  for  a  few  days.  In  all  my  cases  since  these 
were  reported  I  have  not  had  any  trouble  with  the  heal- 
ing of  the  wound  and  the  absorption  of  the  suture.  I 
have  had  Meyrowitz  prepare  the  sterilized  catgut  for  me 
and  put  it  in  small  capsules,  each  containing  a  sufficient 
quantity  for  one  operation  ;  for  we  can  only  depend  upon 
it  being  readily  absorbed  when  it  is  perfectly  sterilized. 

In  concomitant  squint,  either  convergent  or  divergent, 
with  amblyopia,  I  put  in  the  suture  and  then  cut  the 
opposing  muscle  before  the  suture  is  tied,  thereby  com- 
pleting the  operation  and  placing  the  eye  in  its  proper 
position  with  but  one  operation. 

•  The  suture  can  be  easily  applied  under  the  anesthetic 
effect  of  cocaine,  except  in  young  children,  when  I  prefer 
to  do  it  while  they  are  under  ether. 

Fifty  years  ago,  before  Donders'  made  his  great  discov- 
ery that  asthenopia  was  due  to  hyperopia,  the  surgeons 
of  that  day  frequently  performed  tenotomy  of  the  lat- 
eral muscles  for  the  relief  of  asthenopia,  and  in  many 
cases  gave  relief ;  but  Bonders'  discovery  seems  to  have 
changed  the  opinions  of  the  ophthalmic  surgeons,  and  we 
now  depend  on  glasses  for  relief  in  all  cases.  But  modern 
methods  of  investigation  have  proved  that  while  many 
patients  are  relieved  by  glasses,  still  there  are  those 
which  we  meet  with  very  frequently  that  do  not  derive 
the  expected  relief  from  their  glasses  ;  and  when  we  do 
find  a  decided  want  of  balance  in  the  power  of  the  mus- 
cles, compared  with  that  of  the  normal  proportion,  as 
stated  in  a  pap*er  by  myself  in  the  Medical  Record  of  July 
21,  1894,  we  are  then  justified  in  an  operative  procedure 
which  will  relieve  the  asthenopia. 

In  cases  of  muscular  asthenopia  I  depend  entirely  upon 
the  prism  tests  and  the  findings  of  the  tropometer  for 
indications  in  the  use  of  the  suture,  for  we  should  not 


OPERA  TIONS.  I  5  5 

deprive  the  eyes  of  their  most  useful  function,  the  guid- 
ing sensation  or  fusion  power. 

There  has  been  so  much  opposition  in  the  profession 
to  the  partial  and  graduated  tenotomies,  and  still  further 
so  many  failures,  that  some,  I  think,  have  perhaps  ceased 
to  operate  ;  but  I  do  not  believe  the  same  objections  can 
hold  in  the  case  of  this  procedure.  It  can  be  applied  to 
so  many  cases  of  insufficiency  of  the  straight  muscles 
without  the  least  danger  of  overcorrection  or  producing 
squint,  that  I  offer  it  to  the  profession  for  a  fair  and  com- 
plete trial. 

ADVANCEMENT  OF  AN  OCULAR  MUSCLE.  —  I  think  the 
results  of  this  procedure  are  greater  than  that  of  other 
operations,  and  it  is  generally  indicated  in  extreme  diver- 
gent squint.  The  first  steps  of  the  operation  are  similar 
to  those  of  shortening,  until  the  muscle  is  exposed  on  the 
two  hooks.  Then  I  prefer  to  follow  the  suggestion  of 
Prince,  whose  operation  is  called  "  the  single  suture  "  or 
"  pulley "  method.  The  operation  requires  great  care 
and  attention  to  detail,  but  the  results  are  very  satisfac- 
tory and  the  method  removes  that  possibility  of  produc- 
ing torsion  by  tying  one  suture  tighter  than  the  other  as 
in  the  old  methods,  when  two  or  more  sutures  are  used. 
In  performing  this  operation,  I  have  exposed  the  muscle 
to  be  advanced  on  the  two  strabismus  hooks,  as  in  the 
shortening  operation.  While  these  two  hooks  are  held 
by  an  assistant,  we  take  a  black  silk  suture  armed  with 
two  small  needles  and  pass  one  through  the  upper  part  of 
the  muscular  tissue,  and  the  other  below  at  an  opposite 
point  from  without  inward,  and  as  far  backward  in  the 
muscular  tissue  as  needed.  This  forms  a  loop,  which  with 
the  two  ends  are  now  taken  in  one  hand,  the  hooks 
removed,  and  the  tendon  completely  severed  from  its 
attachment.  The  loop  is  now  laid  aside  and  the  upper 
needle  is  passed  deeply  into  the  sub-conjunctival  tissue 


156  STRABISMUS. 

beneath  the  conjunctiva  until  it  emerges  above  the 
cornea  about  three  or  four  millimeters  in  the  vertical 
meridian  of  the  eye.  The  lower  needle  is  now  passed 
below  in  the  same  way,  coming  out  at  an  opposite  point 
below  the  cornea.  We  may  now  take  either  needle  and 
carry  it  back  through  the  loop  and  then  this  loop  is 
drawn  down  tightly  over  the  thread.  Now  carry  the 
suture  back  towards  the  other  end,  and  as  these  are  tied 
it  will  be  readily  seen  that  the  cut  end  of  the  muscle  and 
tendon  must  advance  toward  the  edge  of  the  cornea.  An 
assistant  may  rotate  the  eyeball  in  an  opposite  direction 
at  the  same  time,  so  as  not  to  put  too  much  strain  on  the 
tissues  as  the  suture  is  tied.  Any  overlapping  of  the  con- 
junctiva on  the  cornea  will  disappear  when  the  sutures 
are  removed.  By  passing  the  suture  in  this  continuous 
manner  through  the  loop  or  pulley,  the  movements  of  the 
eye  will  soon  adjust  the  tension  above  and  below,  and  so 
prevent  torsion  on  the  optic  axis.  The  effects  of  this 
operation  is  very  decided  in  the  change  of  the  position  of 
the  visual  line.  In  very  marked  divergent  squint,  this 
operation  should  be  performed  in  all  cases,  and  may  be 
done  on  both  interni  at  one  sitting.  Landolt  recommends 
this  operation  in  all  cases  of  squint,  and  it  has  also  been 
warmly  advocated  by  Wooten  of  this  city,  who  reports 
some  excellent  results.  I  prefer  to  use  it  only  in  cases  of 
excessive  squint.  The  effects  of  this  operation  will  show 
from  20°  to  25°  in  the  change  of  visual  line. 


CHAPTER  XI. 

AFTER    TREATMENT    OF    SQUINT. 

THE  suitable  procedure  with  our  cases  after  the  opera- 
tion has  been  performed  will  depend  on  the  previous 
existing  condition,  that  is  to  say,  whether  our  case  has 
been  one  of  fixed  or  latent  squint.  In  fixed  squint,  when 
the  eyes  are  examined  after  the  operation,  if  there  has 
been  any  over-effect  produced  as  a  slight  divergence,  then 
I  keep  the  eyes  open  and  if  a  shortening  or  advancement 
has  been  made  we  may  loosen  the  suture  if  possible. 
Conversely,  if  we  find  that  the  visual  lines  still  turn 
inward  slightly  it  is  best  to  use  the  solution  of  Atropine 
(grs.  2  to  the  ounce),  instilled  into  both  eyes  so  as  to 
stop  all  action  of  the  accommodation  and  the  refraction 
must  be  fully  corrected  with  glasses.  As  I  do  not  cover 
the  operated  eye  when  protected  in  the  house,  this  pro- 
cedure can  be  instituted  at  the  first  examination.  If  our 
operation  for  heterotropia  has  been  successful  as  far  as 
the  position  of  the  visual  lines  is  concerned  and  the  eyes 
appear  to  be  in  the  first  position  when  fixed  on  infinity, 
then  the  after-treatment  is  the  same  as  follows  in  the 
cases  of  heterophoria,  that  is  to  say,  the  effort  to  improve 
the  fusion  force  and  to  establish  binocular  vision. 

I  consider  the  treatment  of  these  cases,  for  the  correc- 
tion of  muscular  asthenopia,  before  we  have  attempted  the 
correction  of  any  case  of  heterophoria  by  an  operation, 
not  permanent  but  after  the  operation  has  been  performed, 
particularly  so  in  fixed  squint,  orthoptic  treatment  may  be 
very  useful.  After  the  operation  for  fixed  squint,  in  the 


158  STRABISMUS. 

first  class  there  may  exist  that  condition  described  by  Von 
Graefe  as  an  "  antipathy  to  binocular  vision,"  in  other 
words,  while  the  obvious  conditions  may  show  complete 
parallelism  of  the  visual  lines,  yet  true  binocular  vision  is 
not  present  and  the  patient  will  not  see  with  one  eye. 
We  must  remember  that  the  two  eyes  should  act  physio- 
logically as  one  eye,  or  cyclopean  and  unless  there  is  a 
decided  muscular  anomaly  they  must  act  together  and  see 
together.  Hence  we  may  say  it  is  a  natural  function  of 
the  eyes  that  causes  a  non-operated  eye  to  show  the 
effects  of  an  operation  on  the  other  eye  in  the  fields  of 
version  and  fusion,  without  regard  to  the  innervation  that 
may  stimulate  any  one  of  the  ocular  muscles  to  action. 
This  has  been  denied  by  other  writers  but  it  seems  to 
me  that  I  have  found  it  very  noticeable  in  many  of  my 
cases  after  an  operation. 

Now  to  correct  this  "  antipathy "  or  to  improve  the 
fields  of  motion  by  which  we  may  stimulate  the  physio- 
logical part  of  vision  to  become  established,  is  frequently 
a  very  perplexing  problem  and  one  that  will  frequently 
meet  with  failure.  We  may  operate  and  the  tests  may 
show  perfect  movement  of  the  eyes  in  the  field  of  ver- 
sion, but  fusion  of  images,  that  automatic  part  of  the 
act  of  vision,  cannot  be  produced.  To  restore  paral- 
lelism and  produce  perfect  binocular  vision  is  the  ideal 
result  to  be  obtained.  In  some  cases  we  may  succeed ; 
in  others,  the  most  persistent  efforts  will  only  result  in 
failure ;  yet  the  object  to  be  attained  is,  none  the  less, 
necessary  and  useful  to  the  patient,  hence  all  reasonable 
efforts  should  be  instituted  for  its  attainment.  I  have 
had  cases  where  the  results  seem  to  be  excellent  ;  there 
was  no  evidence  of  squint,  yet  I  could  not  develop  the 
slightest  degree  of  binocular  vision.  There  was  HO  field 
of  fusion  whatever.  Such  cases  I  have  generally  found 
in  squint  of  the  first  class,  that  is,  squint  associated  with 


AFTER  TREA  TMENT  OF  SQUINT.  I  59 

congenital  amblyopia.  If  this  condition  exists,  I  am  sat- 
isfied with  a  good  cosmetic  result,  and  make  no  effort 
to  bring  about  binocular  vision  ;  conversely,  if  we  have 
squint  of  the  second  class,  in  which  we  find  fairly  good 
vision  in  each  eye  20-70,  or  better,  then  I  make  every 
reasonable  effort,  that  the  patient  will  permit,  to  restore 
or  produce  binocular  fixation  and  fusion.  The  vision  in 
amblyopia  ex  anopsia  may  be  frequently  improved  by 
treatment,  and  with  the  improvement  of  the  vision  we 
may  find  a  decided  improvement  of  the  fusion  force  with 
eventually  binocular  vision.  Habit  must  play  a  very  in- 
portant  role  in  these  cases.  This  may  be  overcome  and 
corrected  by  persistent  effort.  If  then,  our  operation  has 
been  performed,  the  vision  is  fairly  good  and  improv- 
ing—  what  procedures  are  indicated  ? 

Drugs  will  be  of  little  or  no  value  now,  except  so  far 
as  we  may  improve  the  general  condition  of  the  bodily 
health.  It  goes  without  saying  that  in  all  cases  the 
refraction  must  be  corrected  as  the  first  consideration. 
Exercise  of  the  individual  muscles  is  frequently  of  service. 
This  is  done  by  the  use  of  prisms,  with  the  apex  placed 
over  the  insertion  of  the  muscle  to  be  developed.  Con- 
stant exercise  of  this  kind  will  in  many  cases  improve  the 
fusion  force,  and  may  be  continued  as  long  as  the  results 
show  any  improvement. 

Hansel  and  Reber  (page  108)  claim  that  by  prism 
exercise  the  power  of  adduction  may  be  carried  to  100° 
inside  of  eight  or  ten  weeks.  I  have  never  been  able  to 
bring  about  such  a  happy  result  in  my  cases,  and  it  seems 
to  me  that  a  prism  of  100°  held  properly  before  the  eye 
is  very  close  to  the  "limit  angle,"  unless  two  prisms  are 
used  of  50°  each,  placed  base  outward,  and  if  so,  I  do  not 
think  we  are  stimulating  the  fusion  force  of  the  eyes,  but 
simply  the  convergent  center,  the  same  as  if  the  object 
were  brought  nearer  to  the  eyes,  up  to  the  near  point. 


l6o  STRABISMUS. 

Closing  one  eye  having  the  better  vision,  by  bandage 
or  pad  for  five  or  ten  minutes  every  day,  may  improve 
the  vision  of  the  amblyopia  from  disuse,  though  I  do  not 
like  this  procedure  after  an  operation. 

The  effort  to  blend  the  pictures  of  a  stereoscope  is 
useful,  and  tend  to  improve  the  function  of  the  third 
dimension  if  there  is  any  tendency  to  the  use  of  both 
eyes,  as  in  this  way  we  stimulate  fusion  and  improve  the 
mental  processes  of  the  act  of  vision.  Suitable  pictures 
for  this  purpose  can  be  procured  from  Mr.  E.  B.  Mey- 


WORTH'S  AMBLYOSCOPE. 


rowitz  of  this  city.  Furthermore,  in  the  after-treatment 
of  all  these  cases  of  latent  and  fixed  squint  I  think  the 
amblyoscope  of  Worth,  England,  is  a  very  useful  instru- 
ment. 

I  cannot  fully  approve  of  all  Worth  claims  for  this 
instrument  to  bring  about  fusion,  particularly  before  an 
operation,  as  his  statistics  of  a  large  number  of  cases  do 
not  show  any  larger  percentage  of  corrections  than  that 
by  the  use  of  glasses  ;  but  in  squint  of  the  second  class, 


AFTER   TREATMENT  OF  SQUINT.  l6l 

where  we  have  a  lateral  deviation  or  a  latent  squint,  then 
after  an  operation   I  think  this  instrument  a  very  valuable 
one.      A    full    description    of    its  use   may   be   found   in 
Worth's    monograph  on  squint,    lately    issued.       This  is 
an  excellent  method    of    stimulating  the  habit  of  blend- 
ing the  images  on  each  retina  —  one  of  the  most  inter- 
esting   psychological  functions   of    nature  —  when    they 
tend  to  separate  in  squint,  and  for  the  purposes  of  orthop- 
tic training  for  the  establishment  of  binocular  vision  it  is 
very  useful.     This  instrument  consists  of  two  tubes,  each 
forming  an  angle  of  120°  with  two  oval  mirrors  placed  at 
the  apex  of  the  angle.    At  the  distal  ends  of  the  tubes  are 
grooves    for    holding  the  glass    slides   with  the   pictures 
drawn  on  them.   At  the  proximal  ends  are  two  convex  lens 
whose  focal  distance  is  situated  at  the  pictures,  so  that  the 
rays  entering  the  eyes  will  pass  as  from  infinity.  At  these 
ends   we   also   find  grooves  or  slots  to  hold  any  glasses 
necessary  to  correct  an  error  of  refraction.     These  tubes 
are  joined  by  a  hinge  at  the  proximal  ends,  so  that  they 
may  be  adjusted  to  any  angle  of  squint.     The  object  slides, 
as  the  bird  and  the  cage,  are  simply  to  teach  the  child  to 
see  with  each  eye  the  image  formed  on  each  retina  and 
then  by  moving  the  tubes  the  bird  can  be  made  to  enter 
the  cage.     The  other  slides,  having  only  parts  of  the  pic- 
tures on  them,  with  certain   similar  parts  very  prominent, 
must  be  blended  to  form  a  perfect  picture.     The  slides 
with  the  circles  are  to  be  blended  and  should  also  give  the 
effect  of  solidity  or  the  "third  dimension."     When  these 
images  can  be  readily  blended  the  tubes  are  to  be  moved 
closer  together  to  stimulate    convergence  and  apart  for 
divergence  as  long  as  the   images  do   not   separate.   By 
this   process,  Worth    claims,    we   gradually    increase  the 
power  of  the  eyes  to  blend  the  images  on  the  retina  and 
stimulate    the   retina  to    its   natural    function     from    the 
increase  of  the  field  of  fusion.     This  method  of  treatment 


1 62  STRABISMUS. 

has  some  advantages  over  that  of  the  stereoscopic  pic- 
tures, as  we  can  produce  a  blending  of  the  pictures  at  any 
angle  of  squint  before  an  operation,  or  that  may  remain 
after  the  operation  has  been  performed.  Then  by  the 
gradual  changing  of  the  position  of  the  pictures  we  stimu- 
late the  function  of  blending  until  binocular  vision  may 
be  established.  That  this  practice  requires  an  immense 
amount  of  patience  on  the  part  of  the  surgeon  and  the 
patient  goes  without  saying,  at  the  same  time,  the  ulti- 
mate result  of  binocular  vision  that  may  be  attained  is 
well  worth  a  careful  and  serious  effort.  If  one  eye  is 
amblyopic,  then  when  using  this  instrument  we  may  reduce 
the  illumination  of  the  slide  before  the  eye  with  the  better 
vision,  so  as  to  stimulate  the  vision  of  the  amblyopic  eye, 
and  in  this  way  increase  its  power  to  blend  the  image 
with  that  of  the  other  eye.  The  illumination  of  an  object 
has  a  great  influence  on  the  power  to  fuse  similar  images 
as  well  as  the  power  to  see,  but  as  to  the  value  of  this 
instrument  in  the  correction  of  squint,  of  the  second  class, 
with  fairly  good  vision  in  each  eye,  I  have  had  no  experi- 
ence and  Worth's  statistics  seem  to  me  about  the  same 
as  others  claim  from  the  use  of  glasses  that  will  correct 
the  refractive  error.  In  the  after  treatment  of  squint  I 
think  the  amblyoscope  will  be  very  useful,  as  this  exercise 
must  have  some  influence  on  the  blending  of  images  on 
the  retina  of  each  eye,  as  the  tubes  enable  the  patient  to 
have  single  vision  when  the  visual  lines  are  deviated,  but 
I  do  not  like  the  term  fusion,  as  this  apparatus  does  not 
show  nor  measure  the  field  of  fusion  in  any  way. 

Finally,  all  cases  of  muscular  asthenopia,  and  even  fixed 
squint,  may  be  improved  by  an  active  life  in  the  open  air, 
exercise  and  diet,  but  we  must  consider  all  these  cases 
from  their  individual  lives.  We  cannot  advise  all  our 
cases  of  muscular  asthenopia  to  ride  horseback  or  take 
a  trip  to  Europe,  but  we  must  consider  their  environment 


AFTER   TREATMENT  OF  SQUINT.  163 

and  the  needs  of  their  daily  life.  We  cannot  take  many 
of  them  from  their  daily  occupations  and  duties,  and  so 
our  mode  and  method  of  treatment  must  be  adjusted  to 
the  circumstances  of  our  patients. 


INDEX 

PAGE 

Abduction,          .                                        ....  24,  30 

Action  of  the  Muscles  Under  Innervation,      ...  58 

Action  of  the  Obliques,              .....  29 

Adduction,           .                                                     ...  24,  30 

Advancement  Operation,                                                   .             .  154 

After  Treatment  of  Squint,      .                           ...  156 

Alternating  Squint,        .                                        ...  103 

Amblyoscope.  Worth's,               .             .                           .  159 

Worth's,  Method  of  use,          .             .             .  160 

Amblyopia,         .             .             .             .             ,             .             .  99,  113 

Ex  Anopsia,            .....  98 

Congenital,             .             .             .             .             ,  100 

without  Squint,      .....  101,  103 

"          without  Squint,  Case  of                 ...  130 

Anaphoria,          .......  77 

"  Case  of                 ......  81,  130 

Anatropia,           .......  34 

Anatomical  Theory,       ......  58 

Angle  "  A  "  or  Alpha,    .             .             .             .             .  no 

"  "      size  of  .  .  .  .no 

"         Kappa,               .             .             .             .             .             .  no 

of   Squint,         ......  63 

Apparent  Squint,                          .....  109 

Argument,           .......  2 

Asepsis,                .......  143 

Axes,  Principal  .......  29- 

Binocular  Vision,            ......  16 

Catgut  Suture,                 ......  148 

"         "          Indications  for  Use  of            ...  150 
Check  Ligaments,          .             .             .             .            .            .120 

Classification  of  Squint,            .....  32 

Clinoscope,  Stevens,      ......  87 

165 


1 66  INDEX. 

PAGE 

Clinoscope,  Stevens,  Method  of  Use,  ...  87 

Conjugate  Movements,  .  .  .  .  .  16 

Complete  Tenotomy,  .....  145 

Convergence,  Paralysis  of,         .....  74 

Congenital  Absence  of  Outward  Movements,  .  .  121 

"          Absence  of  Outward  Movements,  Case  of  .  122 

Conclusions  on  Exophoria,       .  .  .  .  .  71 

Condensed  Tables  of  Esophoria,          .  .  .  .  42 

"          Tables  of  Exophoria,  .  .  .72 

Concomitant  Squint,  .  .  .  ,  89 

Convergent  Squint,  Etiology,  .  .  ".  98 

"          Squint,  Cases  of,    .....   151,152 

"  Squint,  with  Myopia,         .  .  .  .125 

"  Squint,  First  Class,  .  .  .  .126 

"          Squint,  Second  Class,        .  .  .  .   125,  126 

"          Squint,  with  Glasses,         .  .  .  .126 

Correction  of  Squint  with  Glasses,      .  .  .  .  107 

Cyclophoria,       .  .  .  .  .  .  31,  85 

Minus,      .  .  .  ,  .  .       35,  86 

Plus, 35,  86 

Cyclotropia,       .  .  .  .  .  .  .  31 

Declination,  Plus  and  Minus,   .             .                           ,             .  86 

Dextroversion,    .             .             .             .                       (  .   •>  3° 

Ductions,             .             .             .             .             .             .             •  3°>  4° 

Divergence,        .......  3° 

Divergent  Squint,           ......  94,  98 

"           Squint,  Latent,         .                          .             .             .  47 

"          Squint,  First  Class,  Case  of            .            .             .  127,152 

"          Squint,  After  an  Operation,            f   *                      .  127 

Divergence,  Paralysis  of            .             .             .             .             .  75 

Donders,  Antithesis       .             .             .                           .             .  89 

Double.  Prism,    .             .             .             .                          .             .  86 

Drugs,                  .......  IS8 

• 

Effect  of  Advancement,  .  ~  ,  .  .  155 

"  of  Operation,  ....  .  .  .  .  146 

Esophoria,          .......  36 

"  Case  of  .  .  .  •   129,  150 

"  Indications  of          ...  .  .  .  41 

"  Symptoms  of  .  .  .  42,  44 


INDEX.  167 

PAGE 

Esophoria,  Treatment  of           .....  43 

Esotropia,            .......  33 

Etiology  of  Convergent  Squint,  .... 

Euphoria,             .......  34 

Examination  with  the  Tropometer,      ....  60 

Exercise  by  Prisms,  for  Interni             ....  69 

Exophoria,          .......  47 

"            Case  of                    .             .             .             .             .  128,  150 

"          and  Myopia,             .....  55 

"           Diagnosis  of            .....  62 

"           Operation  for           .....  70 

"           Prism  Test  for        .....  67 

"           Glasses  for               .....  68 

"           Symptoms  of            .....  61 

"           Treatment  of           .....  68 

"           with  Myopia,  Case  of          ,             ,             .             .  124 

"          with  Kataphoria,  Case  of  ,             .             .             .  124 

Exotropia,           ......  33 

Extorsion,           .......  30 

Eye  Movements,  Types  of 

Field  of  Fixation,          ...                          .             .  19 

"     of   Fusion,              .             ,             .             .             ,             .  23 

"     of  Version,             ......  60 

"     of  Version  with  Perimeter,           ....  63 

First  Position,                 ......  41 

Fixed  Squint,                   .             .             .             .             ,             .  32,  102 

Frontispiece,  Case          ....                          .  132 

Functional  Squint,         .....  89,  101 

Fusion,  .....  .38 

Fusion,  Method  of  Testing,      ...                          .  136 

Glasses  in  Exophoria,    ,             .             .             .             ...  68 

"  Growing  Out  of  a  Squint,"    ,  .  .  .So,  too,  104 

Guiding  Sensation,         .,..,.  26 

Habit,     .  .  .  .    '         .   .  .  .158 

Hansen  Grut  on  Squint,             ,                          .  89 

Heterophoria,                  ......  33 

Heterotropia,                   ......  89 


1 68  INDEX. 

PAGE 

Hubbell  on  Squint,         ....  .89 

Hyper-esophoria,            ......  33 

Hyper-exophoria,           ......  33 

Hyperphoria,      .             ,             .             .             .             .             .  77 

and  Esophoria,  Case  of              .             ,             .  131 

"             Case  of               .             .             .             .             .  80,  128 

"             Influence  on  Squint,      .             ,             ,             .  82 

"             Treatment  of                   .             .             .             .  85 

Hypophoria,       ,             .             .             .             .             ,             .  77 

Hypertropia,       .                                                   ...  33 

Hypotropia,                                                            .             .  33 

Hypo-esophoria,             ......  33 

Hypo-exophoria,             ......  33 

Illustrative  Cases,          .  .  .  .  .  .123 

Illustration,  Exposure  of  the  Muscle,              .             .             .  147 
Suture  in  Position,           .             .             .             .148 

"          Formation  of  the  Tuck,  ....  149 

Improvement  in  Vision,  .  .  .  .  .120 

Indications  for  Operations,       .....  133 

"            of  Esophoria,         .....  41 

"            of  Fixed  Squint,    .             .             .             .  139 

"            for  Treatment,      .....  106 

Insertion  of  Eye  Muscles,         .....  2 

Interni,  Spasm  of                         ,             .             .                           .  42 

Insufficiency  of  Interni,             .....  102 

Innervation  Theory,      ......  89 

Intorsion,             .......  30 

Instruments,       .......  144 

Kataphoria,         .             .             .             .             .             .             .  77 

Katatropia,         .......  34 

Latent  Convergent  Squint,       .....  36 

"       Divergent  Squint,          .....  47 

Squint,                 .                          .                         .             .  32,  103 

"       Vertical  Squint,              .             .            .            .            .  77 

Levoversion,         .......  30 

Maddox  Double  Prism,              .....  86 

"         Simple  and  Compound  Rod,             ...  67 

Maddox  on  Squint,         ......  104 

Method  of  Testing  Fusion,       ,             .             .             ,            .  136 


INDEX.  169 

PAGE 

Minor  Causes  of  Squint,  .... 

Motion,  Planes  of  ..... 

Movements  of  the  Eyes,  .... 

"  of  the  Visual  Axes,  .... 

Myopia  and  Squint,  ..... 

"       and  Hyperphoria,  Case  of          ... 

Natural  Cure  of  Squint,  ....  100,  104 

Ocular  Muscle,  Shortening,           .....  146 

Operations,              .......  142 

Operation  for  Advancement,         .  .  .  .  ,154 

"          for  Fixed  Squint,          .....  108 

"          for  Partial  Tenotomy,              ....  145 

"          for  Tenotomy,               .....  145 

"          for  Shortening,             .             .             .             .             .  146 

Orthoptic  Training,           ......  68 

Orthophoria,           ......  33 

Paralysis  of  Associated  Movements,        .  .  .  .74 

"         of  Convergence,  ,  .  .  .  .74 

"         of  Convergence,  Case  of  .  .  .  .123 

"          of  Divergence,  .  .  .  .  -75 

"          Treatment  of  .....         75 

Paresis  of  Left  Externus,  .....       150 

Partial  Tenotomy,  ......       145 

Periodic  Squint,  ......       102 

Perimeter,  .......         63 

Planes  of  Motion,  ......         29 

Position  of  the  Eyes  under  Ether,  .  .  .  .51 

"        of  rest,  .  .  .  .  .  50,  51 

Preparations  for  Operation,          .  .  .  .  .143 

Prescribing  Prisms,  ......         69 

Preface,  .......          3 

Priestly  Smith  on  Squint,  .  .  .  .  .89 

Primary  Position,  .  .  .  .  .  .49 

Prism  Convergence,  .  .  .  .  .  -3° 

"      Divergence,  ......         30 

Prisms,  set  of         .....  .65 

"          to  order,  ......        69 

"         to  order,  Caution  in,         .  *  .  .  .82 


1 7°  INDEX. 

PAGE 

Prisms,  to  order  in  Exophoria,  .  .  .  .67 

Prism  Test,  .....  65 

Prism  Test  for  Orthophoria,         ...  41 

Principal  Axes,  ......         29 

Region  of  Distinct  Vision,  .....  5 

Relative  Power  of  Muscles,  ,  .  .  ,  .22 

Force,  ......         40 

Report  by  Dr,  Titcomb,  .  .  .  .  .117 

"       by  Dr.  Connors,  ,  .  .  .  ,119 

Restoration  of  Vision  in  Amblyopia,  .  .  (          .113 

Size  of  Eye  Muscles,        .....  2 

Shortening  of  Ocular  Muscles,  ....        146 

Spasmodic  Action  of  Interni,  ....         42 

Squint,  Alternating,          ....  103 

"       Concomitant,         ......          89 

"       Classes  of,  ......         94 

"       Complicated  with  Vertical  Tendency,  .  .         83 

"       Convergent,  ......         89 

"       Divergent,  .....  94,  98 

"       Fixed,  .  .  .  .'••••;  32>  102 

"       Functional,  .  •  .  .  . .  .89 

First  Class,  .....  97,  101 

Indications  in,  .  .  .  .  .139 

Latent,  .  .  .  .  .  32,  103 

"       Latent  Vertical,  .  .  .          .  .  .          77 

"       Second  Class,  ....  98,  101 

Tables  of  ...  .96,  99 

"       Theory  of  .  .....          93 

"       Vertical,  ..... 

"       with  Myopia          .  .  .  .  .  98.  104 

Stereoscope,  .  .  .  .  .  4  .159 

Stevens  Tropometer,        .  ,  .  .  .  ,58 

Strabismus,         •   .  ,  .  .  ,  .  .89 

Subversion,  .......         30 

Subduction,  .  .  .  .  .  .  .30 

Superduction,         .......         30 

Superversion,         .......         30 

Symptoms  of  Esophoria,  .....         44 

"  of  Exophoria,  ,  ,  ^  •»  .         61 


INDEX.  I  7  I 

PAGE 

Tables  of  Esophoria,          ......         45 

"       of  Exophoria,         .  .  .  .  .  .72 

"        of  Squint,  ......          99 

Tendency  to  Right  or  Left,  .  .  .  .  .84 

"          to  Right  or  Left,  Case  of  ...         84 

Tonics,  .......         68 

Torsion,  .......         86 

"      Field  of      .  ,  .  .  .  .  .60 

"       Minus,         .......         86 

"      Plus,  .......         86 

Treatment  of  Fixed  Squint,          .....       107 

of   Esophoria,  ,  .  .  .  .43 

"  of   Exophoria,  ,  .  .  .  .68 

Tropometer,  Stevens,  .  .  .  .  -57 

Twin  Strabismus  Hooks,  .....       148 

Types  of  Eye  Movements,  .....  8 

Versions,  .......         30 

Vergences,  .......         30 

Vertical  Rotation,  ......         83 

Wahlfors  on  Squint,           ......  90 

Worth's  Amblyoscope,      ......  59 

"      Amblyoscope,  Method  of  Use,                .            .            .  160 

"       on  Squint,             ......  90 

"       Test  for  Children,            .                         ...  105 


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